CUET UG Applied Mathematics Booster Test 1 - t-Test & Applications
📌 Answers are locked once submitted — results and explanations appear at the end.
QUESTION 1 OF 20
For a standard t-distribution centered at zero, evaluate the expected value (mean):
\(E(X)=\int_{-\infty }^{\infty }\,x⋅f(x) dx\)
QUESTION 2 OF 20
When the population variance is unknown and estimated using the sample standard deviation S, how does the t-distribution compare to the standard normal (Z) distribution in terms of tail behavior?
QUESTION 3 OF 20
As the absolute value of the calculated t-ratio increases (moves away from 0), what happens to the tail area (p-value) beyond this value?
QUESTION 4 OF 20
Consider a decision vector D = [H₀, H₁].
If a two-tailed test yields a calculated t-value within the interval
\(\left(-t_{crit}, t_{crit}\right)\)
which hypothesis is supported?
QUESTION 5 OF 20
A 3-day moving average gives x̄ = 1.2, tested against μ = 0 with
\(H_{1}:\mu \neq 0\)
What type of test is this?
QUESTION 6 OF 20
Given:
n = 23 ⇒ df = 22, α = 0.01 (left-tailed),
and the one-tailed critical value t = 2.508, determine the correct critical t-value.
QUESTION 7 OF 20
Match the components of the formula
\(t=\frac{\hat{x}-\mu }{S/\sqrt{n}}\)
with their meanings:
| List I | List II |
|---|---|
| 1. x̄ | a. Population mean |
| 2. μ | b. Standard Error |
| 3. S/√n | c. Sample size |
| 4. n | d. Sample mean |
QUESTION 8 OF 20
Assertion (A):
If the calculated value is t = -3.10 and the critical value is t = -2.776, the null hypothesis is rejected.
Reason (R):
The calculated t-value lies further into the rejection region (tail) than the critical value.
QUESTION 9 OF 20
Arrange the following significance levels in increasing order of the probability of a Type I error (from strictest to least strict):
1. 0.10
2. 0.05
3. 0.01
4. 0.20
QUESTION 10 OF 20
Identify the incorrect statement regarding degrees of freedom (df) in t-tests.
QUESTION 11 OF 20
Which of the following effectively differentiate a sample from a population in statistical inference?
I. A sample statistic utilizes English alphabets (x̄, S).
II. A population parameter utilizes Greek alphabets (μ, σ).
III. The sample size is practically always smaller than the entire population's size.
IV. A population acts as an estimation for the smaller sample bounds.
QUESTION 12 OF 20
Using the one-sample t-test formula
\(t=\frac{\hat{x}-{\mu}_{0}}{S/\sqrt{n}}\)
if the sample mean exactly matches the expected population mean (x̄ = μ₀), what is the calculated t-value, and where does it map on the graphical curve?
QUESTION 13 OF 20
An inspector tests 60 fertilizer bags claimed to have a mass of 50 kg. He determines that the sample average is 49.6 kg.
Which numeric values represent the comparison parameter μ₀ and the sample mean x̄, respectively?
QUESTION 14 OF 20
If a researcher conducts a hypothesis test and the conclusion states that we fail to reject the null hypothesis, what does this statistically imply?
QUESTION 15 OF 20
Country A reports an average farm size of 191 acres (n₁ = 8, s₁ = 38).
Country B reports an average farm size of 199 acres (n₂ = 10, s₂ = 12).
For statistical analysis, these two datasets denote:
QUESTION 16 OF 20
Utilizing the data representing Country A and Country B (191 acres and 199 acres), what is the calculated numerator of the independent t-statistic representing the mean difference?
QUESTION 17 OF 20
In the pooled standard deviation formula
\(s_{p}=\sqrt{\frac{(n_{1}-1)s_{1}^{2}+(n_{2}-1)s_{2}^{2}}{n_{1}+n_{2}-2}}\)
what does the denominator n₁ + n₂ − 2 physically represent?
QUESTION 18 OF 20
When solving for unequal variances in a two-sample t-test, the formula adapts its denominator.
What is the standard error component Strategy Used for the difference between two sample means without pooling?
QUESTION 19 OF 20
Based on the passage, which hypothesis must have been rejected to reach this conclusion?
QUESTION 20 OF 20
If the test result leads to accepting the null hypothesis (H₀), what is the appropriate business decision?
Test Complete!
Answer Review
1 For a standard t-distribution centered at zero, evaluate the expected value (mean):
\(E(X)=\int_{-\infty }^{\infty }\,x⋅f(x) dx\)
Standard t-distribution is symmetric about zero Positive and negative areas balance Mean of symmetric distribution equals zero
The standard t-distribution is centered symmetrically around zero. Because the density function satisfies symmetry: \(f(-x)=f(x)\) the positive and negative contributions in the expected value cancel each other. Thus: \(E(X)=0\) Therefore, Option D is correct.
- Option A → Total probability equals 1, not the mean.
- Option B → α represents significance level, unrelated to expected value.
- Option C → Degrees of freedom are parameters, not the mean.
Used
- Dimensional/Unit Analysis
Application:
- Use symmetry properties of probability distributions.
Final Logic:
- Symmetric distributions centered at zero have mean zero.
"Centered Curve → Mean Zero"
2 When the population variance is unknown and estimated using the sample standard deviation S, how does the t-distribution compare to the standard normal (Z) distribution in terms of tail behavior?
t-distribution accounts for uncertainty in variance estimation More probability exists in tails Heavy tails reduce with larger sample sizes
The t-distribution has heavier (thicker) tails than the standard normal distribution because the population variance is unknown and estimated from sample data. This extra uncertainty increases the probability of observing extreme values. Therefore, Option A is correct. As sample size increases, the t-distribution gradually approaches the standard normal distribution.
- Option B → t-distribution tails are heavier, not thinner.
- Option C → Shapes become similar only for very large samples.
- Option D → Probabilities never suddenly become zero at t = 3.
Used
- Contextual/Tonal Matching
Application:
- Connect "unknown variance" with "extra uncertainty."
Final Logic:
- More uncertainty produces thicker tails.
"Unknown σ → Heavy Tails"
3 As the absolute value of the calculated t-ratio increases (moves away from 0), what happens to the tail area (p-value) beyond this value?
Larger t-values move deeper into tails Tail probability shrinks Smaller p-values imply stronger evidence
The p-value represents the probability of observing a value as extreme as the calculated t-statistic. As: \(∣t∣↑\) the tail area beyond that value becomes smaller. Thus, the p-value decreases. Therefore, Option B is correct.
- Option A → Tail probabilities decrease rather than increase.
- Option C → p-values vary depending on t-values.
- Option D → Tail probability can never equal the entire probability area.
Used
- Contextual/Tonal Matching
Application:
- Associate extreme t-values with shrinking tail probabilities.
Final Logic:
- Bigger |t| means smaller p-value.
"Extreme t → Tiny p"
4 Consider a decision vector D = [H₀, H₁].
If a two-tailed test yields a calculated t-value within the interval
\(\left(-t_{crit}, t_{crit}\right)\)
which hypothesis is supported?
Values inside critical limits are non-significant No sufficient evidence against H₀ Null hypothesis is retained
In a two-tailed test, the rejection regions lie outside the critical values. If: \(-t_{crit}<t_{calc}<t_{crit}\) then the calculated t-value lies in the acceptance region. Thus, we fail to reject H₀. Therefore, Option C is correct.
- Option A → Statistical decisions do not support both simultaneously.
- Option B → H₁ is supported only in rejection regions.
- Option D → One hypothesis must guide the decision.
Used
- Elimination
Application:
- Identify whether the t-value lies inside or outside rejection regions.
Final Logic:
- Inside boundaries implies fail to reject H₀.
"Inside Limits → Keep H₀"
5 A 3-day moving average gives x̄ = 1.2, tested against μ = 0 with
\(H_{1}:\mu \neq 0\)
What type of test is this?
"Not equal to" implies two directions Both tails are tested Rejection regions occur on both sides
The alternative hypothesis uses: \(\mu \neq 0\) The symbol "≠" means deviations in both positive and negative directions are important. Therefore, the hypothesis test is two-tailed. Thus, Option D is correct.
- Option A → Left-tailed uses "<".
- Option B → Right-tailed uses ">".
- Option C → Two critical points exist in two-tailed tests.
Used
- Symbol Recognition
Application:
- Identify the inequality sign Strategy Used in H₁.
Final Logic:
- "≠" always indicates a two-tailed test.
"≠ Means Two Tails"
6 Given:
n = 23 ⇒ df = 22, α = 0.01 (left-tailed),
and the one-tailed critical value t = 2.508, determine the correct critical t-value.
Left-tailed tests use negative critical values Magnitude remains same Sign changes according to tail direction
For a left-tailed t-test, the rejection region lies in the negative tail. Thus, if the table gives: \(t=2.508\) the critical value becomes: \(t=-2.508\) Therefore, Option A is correct.
- Option B → Positive critical value belongs to right-tailed tests.
- Option C → Incorrect numerical value.
- Option D → Incorrect table value.
Used
- Substitution
Application:
- Apply sign convention for left-tailed tests.
Final Logic:
- Left tail always uses negative critical values.
"Left Tail → Negative t"
7 Match the components of the formula
\(t=\frac{\hat{x}-\mu }{S/\sqrt{n}}\)
with their meanings:
| List I | List II |
|---|---|
| 1. x̄ | a. Population mean |
| 2. μ | b. Standard Error |
| 3. S/√n | c. Sample size |
| 4. n | d. Sample mean |
x̄ denotes sample mean μ denotes population mean S/√n is the standard error
The components represent: • x̄ → sample mean • μ → population mean • S/√n → standard error • n → sample size Thus: 1-d, 2-a, 3-b, 4-c Therefore, Option B is correct.
- Option A → Incorrectly swaps x̄ and μ.
- Option C → Mislabels standard error and sample size.
- Option D → Incorrect mapping of all core symbols.
Used
- Option Grouping
Application:
- Match standard statistical notation systematically.
Final Logic:
- Statistical symbols have fixed meanings.
"x̄ = sample, μ = population"
8 Assertion (A):
If the calculated value is t = -3.10 and the critical value is t = -2.776, the null hypothesis is rejected.
Reason (R):
The calculated t-value lies further into the rejection region (tail) than the critical value.
Calculated value is more extreme Rejection region lies beyond critical value Evidence opposes H₀
Since: \(-3.10<-2.776\) the calculated t-value lies deeper in the rejection region. Thus, H₀ is rejected. Reason R correctly explains why the rejection occurs. Therefore, Option C is correct.
- Option A → Both statements are statistically correct.
- Option B → Reason correctly explains the assertion.
- Option D → Assertion is also true.
Used
- Substitution
Application:
- Compare the numerical locations of t-values on the number line.
Final Logic:
- More extreme tail value implies rejection.
"Further Tail → Reject"
9 Arrange the following significance levels in increasing order of the probability of a Type I error (from strictest to least strict):
1. 0.10
2. 0.05
3. 0.01
4. 0.20
Smaller α means stricter testing Larger α increases Type I error risk Arrange from smallest to largest α
Type I error probability equals α. Increasing order: \(0.01<0.05<0.10<0.20\) Thus, the correct arrangement is: 3 → 2 → 1 → 4 Therefore, Option B is correct.
- Option A → Begins with larger α instead of smallest.
- Option C → Incorrect middle ordering.
- Option D → Completely reversed strictness order.
Used
- Dimensional/Unit Analysis
Application:
- Treat α directly as probability magnitude.
Final Logic:
- Smaller α means stricter hypothesis testing.
"Small α = Strict Test"
10 Identify the incorrect statement regarding degrees of freedom (df) in t-tests.
Higher df improves statistical power Lower df increases uncertainty df reflects free information values
Lower degrees of freedom produce wider t-distributions with heavier tails, reducing statistical power. Higher df generally improves estimation precision and increases the ability to reject false null hypotheses. Thus, Option A is incorrect. Options B, C, and D correctly define degrees of freedom in t-tests.
- Option B → Correct formula for one-sample t-tests.
- Option C → Correct pooled df formula for equal variances.
- Option D → Standard definition of degrees of freedom.
Used
- Extreme Word Filter
Application:
- Detect the misleading implication that "lower df" improves power.
Final Logic:
- Larger samples and larger df generally improve power.
"Higher df → Higher Power"
11 Which of the following effectively differentiate a sample from a population in statistical inference?
I. A sample statistic utilizes English alphabets (x̄, S).
II. A population parameter utilizes Greek alphabets (μ, σ).
III. The sample size is practically always smaller than the entire population's size.
IV. A population acts as an estimation for the smaller sample bounds.
Sample statistics use English symbols Population parameters use Greek symbols Samples are subsets of populations
Statement I is correct because sample statistics are commonly represented using English alphabets like: \(\hat{x}, S\) Statement II is correct because population parameters use Greek symbols such as: \(\mu , \sigma\) Statement III is also correct because a sample is generally smaller than the population. Statement IV is incorrect because samples estimate populations, not the reverse. Therefore, Option B is correct.
- Option A → Omits correct Statements II and III.
- Option C → Includes incorrect Statement IV.
- Option D → Statement IV is conceptually wrong.
Used
- Elimination
Application:
- Remove options containing the incorrect Statement IV.
Final Logic:
- Samples estimate populations, not populations estimating samples.
"Greek = Population, English = Sample"
12 Using the one-sample t-test formula
\(t=\frac{\hat{x}-{\mu}_{0}}{S/\sqrt{n}}\)
if the sample mean exactly matches the expected population mean (x̄ = μ₀), what is the calculated t-value, and where does it map on the graphical curve?
Equal means produce zero numerator t-value becomes zero Zero lies at the center of the distribution
If: \(\hat{x}={\mu}_{0}\) then: \(\hat{x}-{\mu}_{0}=0\) Thus: \(t=0\) The value t = 0 lies exactly at the center (peak/apex) of the symmetric t-distribution curve. Therefore, Option C is correct.
- Option A → t = 1 is not obtained when means are equal.
- Option B → Negative t-values arise when sample mean is smaller.
- Option D → α is a probability level, not a t-statistic.
Used
- Substitution
Application:
- Substitute x̄ = μ₀ directly into the formula.
Final Logic:
- Zero numerator gives t = 0.
"Equal Means → Zero t"
13 An inspector tests 60 fertilizer bags claimed to have a mass of 50 kg. He determines that the sample average is 49.6 kg.
Which numeric values represent the comparison parameter μ₀ and the sample mean x̄, respectively?
Claimed value acts as population parameter Sample average acts as sample mean n = 60 is sample size only
The claimed population mean is: \({\mu}_{0}=50\) The calculated sample average is: \(\hat{x}=49.6\) Thus, μ₀ = 50 and x̄ = 49.6. Therefore, Option D is correct.
- Option A → Reverses the meanings of μ₀ and x̄.
- Option B → 60 is the sample size, not the sample mean.
- Option C → Incorrect ordering of values.
Used
- Contextual/Tonal Matching
Application:
- Distinguish between claimed population value and observed sample average.
Final Logic:
- Claimed mean = μ₀, observed average = x̄.
"Claim = μ₀, Observation = x̄"
14 If a researcher conducts a hypothesis test and the conclusion states that we fail to reject the null hypothesis, what does this statistically imply?
Failure to reject H₀ does not prove H₀ true Evidence is insufficient for H₁ Statistical support for difference is lacking
Failing to reject the null hypothesis means that the sample evidence is not strong enough to support the alternative hypothesis. It does not mean H₀ is absolutely true; it simply means insufficient evidence exists against it. Therefore, Option A is correct.
- Option B → Failure to reject H₀ does not imply calculation error.
- Option C → Population variance is unrelated to the decision statement.
- Option D → Standard error does not become infinite.
Used
- Elimination
Application:
- Remove extreme or mathematically impossible interpretations.
Final Logic:
- Fail to reject H₀ means weak evidence against H₀.
"No Reject ≠ Proven True"
15 Country A reports an average farm size of 191 acres (n₁ = 8, s₁ = 38).
Country B reports an average farm size of 199 acres (n₂ = 10, s₂ = 12).
For statistical analysis, these two datasets denote:
Two separate countries form separate samples Observations are unrelated Independent sample comparison applies
The farm-size data come from two different countries. The observations in one group do not depend on observations in the other group. Thus, the datasets represent two independent groups. Therefore, Option B is correct.
- Option A → Paired samples require linked observations.
- Option C → Two groups are compared, not one sample against a parameter.
- Option D → The datasets remain separate groups.
Used
- Odd One Out
Application:
- Identify whether observations are related or independent.
Final Logic:
- Different countries imply independent groups.
"Separate Groups → Independent Test"
16 Utilizing the data representing Country A and Country B (191 acres and 199 acres), what is the calculated numerator of the independent t-statistic representing the mean difference?
Independent t-tests compare means Numerator equals mean difference Subtract one sample mean from another
The numerator of the independent t-statistic is: \(\hat{x}_{1}-\hat{x}_{2}\) Substituting values: \(191-199=-8\) Thus, the numerator equals -8. Therefore, Option C is correct.
- Option A → Means are not added in the t-statistic numerator.
- Option B → Standard deviations are unrelated to numerator calculation.
- Option D → Sample size difference is irrelevant here.
Used
- Substitution
Application:
- Directly substitute group means into the numerator formula.
Final Logic:
- Mean difference equals 191 − 199.
"t Numerator = Mean Difference"
17 In the pooled standard deviation formula
\(s_{p}=\sqrt{\frac{(n_{1}-1)s_{1}^{2}+(n_{2}-1)s_{2}^{2}}{n_{1}+n_{2}-2}}\)
what does the denominator n₁ + n₂ − 2 physically represent?
Pooled variance combines two samples Degrees of freedom are added together Minus 2 accounts for estimated means
In pooled variance estimation: \(df=n_{1}+n_{2}-2\) This quantity represents the combined pooled degrees of freedom from both samples. The subtraction of 2 occurs because two sample means are estimated. Therefore, Option D is correct.
- Option A → Mean difference is unrelated to the denominator.
- Option B → Alpha level is unrelated to pooling.
- Option C → Total sample size would be n₁ + n₂ only.
Used
- Contextual/Tonal Matching
Application:
- Associate pooled variance formulas with pooled df formulas.
Final Logic:
- Denominator equals pooled degrees of freedom.
"n₁+n₂−2 = pooled df"
18 When solving for unequal variances in a two-sample t-test, the formula adapts its denominator.
What is the standard error component Strategy Used for the difference between two sample means without pooling?
Unequal variances avoid pooled SD Variances are handled separately Standard errors are added inside root
For unequal variance t-tests, the standard error for mean difference is: \(SE=\sqrt{\frac{s_{1}^{2}}{n_{1}}+\frac{s_{2}^{2}}{n_{2}}}\) This formula independently accounts for both sample variances without pooling. Therefore, Option A is correct.
- Option B → Standard errors are combined using addition under a square root.
- Option C → Variances alone do not produce standard error.
- Option D → Uses pooled SD, inappropriate for unequal variances.
Used
- Option Grouping
Application:
- Identify the formula specifically Strategy Used in unequal variance testing.
Final Logic:
- Separate variances remain separate inside the square root.
"Unequal Variance → Separate Variance Terms"
19
Based on the passage, which hypothesis must have been rejected to reach this conclusion?
Significant difference supports H₁ Rejecting H₀ allows acceptance of H₁ Null hypothesis assumes no difference
The null hypothesis states: \(H_{0}:{\mu}_{1}={\mu}_{2}\) A statistically significant difference implies sufficient evidence against H₀. Thus, H₀ must be rejected to support the conclusion of unequal means. Therefore, Option B is correct.
- Option A → H₁ is supported, not rejected.
- Option C → Both hypotheses cannot be rejected simultaneously.
- Option D → A significant result requires rejecting H₀.
Used
- Contextual/Tonal Matching
Application:
- Link "significant difference" directly with rejection of H₀.
Final Logic:
- Significant differences contradict the null hypothesis.
"Difference Found → Reject H₀"
20
If the test result leads to accepting the null hypothesis (H₀), what is the appropriate business decision?
Accepting H₀ means insufficient evidence of difference Superiority is not statistically established Decisions should follow evidence
If H₀ is accepted (or fail to reject H₀), the test does not provide sufficient evidence that the new shoe lasts longer than the legacy model. Thus, the company cannot scientifically claim superiority. Therefore, Option C is correct.
- Option A → No evidence supports discontinuation.
- Option B → Statistical superiority was not demonstrated.
- Option D → Manipulating statistics is scientifically invalid.
Used
- Elimination
Application:
- Remove exaggerated or unethical conclusions unsupported by evidence.
Final Logic:
- Accepting H₀ means insufficient proof of improvement.
"No Reject → No Proof"
