Question

According to a University Center for Logistics Management, 13% of all merchandise sold in the United States gets returned. A Seattle department store sampled 90 items sold in January and found that 10 of the items were returned.

If you have the following null and alternative hypotheses for a test you are running:

H 0 : p = 0.13

H a : p > 0.13

Calculate the test statistic, rounded to 3 decimal places z =

Answer 1

Null hypothesis : H_o : p=0.13

Alternate hypothesis : H_a: p >0.13

Right tailed test:

Number of items sampled : sample size : n= 90

Number of items of the sampled items returned : x = 10

Sample proportions of items returned : =x/n = 10/90 =  0.1111

Hypothesized proportion : p_o = 0.13

test statistic

z = -0.533