Question

A manufacturer receives parts from two suppliers. An SRS of 400 parts from supplier 1 finds 20 defective; an SRS of 100 parts from supplier 2 finds 10 defective. Let p1 and p2 be the proportion of all parts from suppliers 1 and 2, respectively, that are defective. Is there evidence of a difference in the proportion of defective parts produced by the two suppliers? To make this determination, you test the hypotheses H0 : p1 = p2 and Ha : p1 ≠ p2. The P-value of your test is

0.1164. 0.0301. 0.0602.

A bank wants to get new customers for their credit card. They try two different approaches in their marketing campaign. The first promises a "cash back" reward; the second promises low interest rates. A sample of 500 people is mailed the first brochure; of these, 100 get the credit card. A separate sample of 500 people is mailed the second brochure; 125 get the credit card. Is there evidence of a difference in the two campaigns? Find the test statistic.

z = –1.89 z = 2.80 z = 0.25

A poll finds that 54% of the 600 people polled favor the incumbent. Shortly after the poll is taken, it is disclosed that the incumbent had an extramarital affair. A new poll finds that 50% of the 1030 polled now favor the incumbent. We want to know if his support has decreased. The test statistic is
	z = –1.55. z = –2.57. z = 1.56

Answer 1

Solution :

Given

n1 = 400 sample size of supplier 1

n2 = 100 sample size of supplier 2

X1 = 20 defective parts

X2 = 10. defective parts of supplier 2

proportion of defective of supplier 1

proportion of defective of supplier 2

To test

Vs  

Test Statistics

Where

Z = - 1.88311

Z= - 1.88

P value = 0.0602

2) Given

n1 = 500 sample size

n2 = 500 sample size

X1 = 100

X2= 125

proportion of cashback rewards

proportion of low interest rates

To test

. Vs.

Z= - 1.893207

Z= - 1.89

3) Given

n1 = 600 sample size

n2 = 1030

To test

Ho p1= p2 vs. Ha : p1 < p2

Test Statistics

q hat = 0.485

Z= 1.5585366

Z= 1.56