Question

A recent study of two vendors of desktop personal computers reported that out of 831 units sold by Brand A, 122 required repair, while out of 749 units sold by Brand B, 114 required repair. Round all numeric answers to 4 decimal places.

1. Calculate the difference in the sample proportion for the two brands of computers, p^BrandA−p^BrandBp^BrandA−p^BrandB = .

2. What are the correct hypotheses for conducting a hypothesis test to determine whether the proportion of computers needing repairs is different for the two brands.

A. H0:pA−pB=0H0:pA−pB=0 , HA:pA−pB>0HA:pA−pB>0
B. H0:pA−pB=0H0:pA−pB=0 , HA:pA−pB<0HA:pA−pB<0
C. H0:pA−pB=0H0:pA−pB=0 , HA:pA−pB≠0HA:pA−pB≠0

3. Calculate the pooled estimate of the sample proportion, p^p^ =

4. Is the success-failure condition met for this scenario?

A. Yes
B. No

5. Calculate the test statistic for this hypothesis test. ?ztX^2F =

6. Calculate the p-value for this hypothesis test, p-value = .

7. What is your conclusion using αα = 0.01?

A. Do not reject H0H0
B. Reject H0H0

8. Compute a 99 % confidence interval for the difference p^BrandA−p^BrandBp^BrandA−p^BrandB = ( , )

Answer 1

1)

difference in the sample proportion for the two brands of computers =-0.0054

2)

C. H0:pA−pB=0H0:pA−pB=0 , HA:pA−pB≠0HA:pA−pB≠0

3) pooled estimate of the sample proportion, =0.1494

4) A. Yes

5) e test statistic for this hypothesis test z =-0.30

6) p-value for this hypothesis test =0.7642

7) A. Do not reject H0

8) 99 % confidence interval for the difference -0.0517 ; 0.0409 (try -0.0518 ; 0.0410 ; if this comes wrong)