.

Alasala Colleges
Deanship of Support Studies
Dammam, Saudi Arabia

STAT

2

02 – Midterm -A-
Spring 2020

• You have to upload your work sheet on LMS in order to receive full credit.

• Remember that any correct answer without supporting work will not receive full credit.

• The exam will be scored out of

3

0 points.

For questions

1

-2:

Assuming the population of interest is approximately normally distributed. Given x̄ = 18.4,
S = 4.2 and n = 13.

1. The point estimate for the population mean is

a) 4.2 b) 13 c) 18.4 d) non

2. The 80 % confidence interval estimate for the population mean is

a) (15.345, 19.455) b) (16.345, 19.455) c) (15.345, 17.455) d) (16.82, 19.98)

3. A manager wishes to estimate a population mean using a 80% confidence interval estimate
that has a margin of error of 44. If the population standard deviation is thought to be
680, the required sample size is

a) 430 b) 340 c) 493 d) 392

For questions 4-7:

For the following hypothesis test:

H0 : π ≥ 0.75
Ha : π < 0.75

with n = 100, p = 0.66 and significance level 0.017.

4. The distribution that is used to perform the test is

a) t distribution

b) Chi distribution

c) F distribution

d) Standard Normal Distribution

5. The critical value for this test.

a) −2.12 b) 2.12 c) 2.39 d) ±2.12

1

6. The test statistic value for this test is

a) −2.0785 b) −4.6188 c) 2.0785 d) 4.6188

7. The conclusion of the test is

a) reject H0 b) do not rejectH0 c) accept Ha d) non

For questions 8-11:

A premium golf ball production line must produce all of its balls with weight 1.615 ounces and
the standard deviation is 0.065 ounces in order to get the top rating The managers must shut
down the production line if it gets out of sync with a statistical. The managers select a random
sample of 18 balls with a mean of 1.611 ounces to test whether they are meeting requirements.
The the significance level is given to be 0.01.

8. State the appropriate null and alternative hypotheses.

a) H0 : µ ≥ 1.615
Ha : µ < 1.615

b) H0 : µ ≤ 1.615
Ha : µ > 1.615

c) H0 : µ = 1.615
Ha : µ 6= 1.615

d) H0 : µ 6= 1.615
Ha : µ = 1.615

9. The critical value for this test.

a) −2.58 b) 2.58 c) 2.85 d) ±2.58

10. The test statistic value for this test is

a) −0.26 b) 0.26 c) 0.24 d) −0.24

11. Should the managers shut down the line production?

a) no b) yes c) do not know d) not clear

For questions 12-14:
Given the following null and alternative hypotheses with the sample means as shown in the
table.

Sample 1 Sample 2
n1 = 40 n2 = 50
x̄1 = 144 x̄1 = 129
σ1 = 11 σ2 = 12

H0 : µ1 ≤ µ2
Ha : µ1 > µ2
α = 0.017

12. The critical value for this test.

a) −2.12 b) 2.12 c) 2.39 d) ±2.12

13. The test statistic value for this test is

a) 5.816 b) 6.173 c) 2.710 d) 0.903

2

14. The conclusion of the test is

a) reject H0 b) do not rejectH0 c) accept Ha d) non

15. The given information is based on independent random samples taken from two normally
distributed populations having equal variances: Based on the sample information, the
90% confidence interval estimate for the difference between the two population means is

Sample 1 Sample 2
n1 = 15 n2 = 11
x̄1 = 50 x̄2 = 53
S1 = 5 S2 = 6

a) (−0.312, 6.312) b) (−5.65, 1.65) c) (−6.694, 0.694) d) (−1.65, 5.65)

3