STA301 Quiz 4 by VU Topper RM

Inferential statistics involves:

A. All of these

B. Estimation C. Confidence interval D. Testing of hypothesis

Conventionally, the probability of making a type-II error is denoted by:

A. ß (beta)

B. Ɵ (theta) C. a (alpha) D. б (sigma)

For a sample of size 20 taken from a normally distributed population with standard deviation equal to 5, a 90% confidence interval for the population mean would require the use of: A. t = 1.328 B. t = 2.12 C.

t = 1.729

D. z = 1.645

The level of significance is also called: A. Acceptence region B. Power of test C.

Type I error

D. Type II error

The proportion of working females in Pakistan is at most 0.40,the null hypothesis Ho<0.40 the alternative hypothesis H1 is: A. P = 0.40 B.

P > 0.40

C. P ≠ 0.40 D. P < 0.40 Suppose that the workers of factory B believe that the average income of the workers of factory A exceeds their average income; the null hypothesis will be: A.

MeanA ≤ MeanB

B. MeanA < MeanB C. MeanA ≥ MeanB D. MeanA > MeanB

The proportion of cigarette smokers in Pakistan is greater than 20%, the null hypothesis Ho is: A.

P ≤ 0.20

B. P > 0.20 C. P < 0.20 D. P ≠ 0.20

The test statistic to test the U1 = U2 (U represent the mean of population)for normal population when n>30. A. All of Above B. T-Test C.

Z-Test

D. F-Test

The degrees of freedom associated with paired t-test ……… A. n1-2 and n2-2 B.

n-1

C. n1+n2-4 D. n-2

As sample size goes up, what tends to happen to 95% confidence intervals?

A.

They become more precise and narrow

B. They become more narrow C. They become wider D. They become more precise

The confidence intervals become wide and less precise by A. increasing the sample size B.

decreasing the sample size

C. decreasing the level of significance D.

at 0.05 level of significance and n > 30 is: A. Z less and equal 1.96 B. Z> 1.96 C.

Z>1.645

D. Z<-1.645

An industrial designer wants to determine the average amount of time it takes an adult to assemble an “easy to assemble” toy. A sample of 16 times yielded an average time of 19.92 minutes, with a population standard deviation equal to 5.73. Assuming normality of assembly times, what is a 95% confidence interval for the mean assembly time? A. (14.1123, 22.7277) B. (17.1123, 24.7277) C.

(17.1123, 22.7277)

D. (17.1123, 30.7277)

If we are testing H0: u 1 - u2 = 20 against H1: u 1 - u2 > 20 (exceeds

20. .Then rejection region will be:

A. in Center B. C. D.