Question

1.

For this problem you will need a t-table. What is the t-value needed for a confidence interval with a sample size = 25 and alpha =.05?

Group of answer choices

2.064

2.060

1.708

1.706

2.

Small Sample Mean Problem. The maker of potato chips uses an automated packaging machine to pack its 20-ounce bag of chips. At the end of every shift 18 bags are selected at random and tested to see if the equipment needs to be readjusted. After one shift, a sample of 18 bags yielded the following data.    mean = 20.45   s = .80   n = 18.

If we were to conduct a test to see if the sample estimate is different from the company’s expected weight of 20 oz. at an alpha level = .05, what is the conclusion for this test?

Group of answer choices

We can reject the null hypothesis that mu = 20

We fail to reject the null hypothesis that mu = 20

We need a bigger sample size to reach a conclusion.

We can accept the alternative hypothesis that mu > 20

Answer 1

Q1:

n = 25

At α = 0.05 and df = n-1 = 24, two tailed critical value, t-crit = T.INV.2T(0.05, 24) = 2.064

----

Q2;

x̅ = 20.45, s = 0.8, n = 18  

Null and Alternative hypothesis:  

Ho : µ =    20

H1 : µ ≠    20

Test statistic:  

t = (x̅ - µ)/(s/√n) = (20.45 - 20)/(0.8/√18) =    2.3865

df = n-1 =    17

p-value = T.DIST.2T(ABS(2.3865), 17) =    0.0289

Decision:  

p-value < α, Reject the null hypothesis.  

Answer: We can reject the null hypothesis that mu = 20