1. A random sample of 200 items yields 35 that are non-conforming. Find the 90% confidence interval for the true population proportion non-conforming.

(0.131) , (0.044)

Step-by-step explanation:

Given:

Total sample n = 200

Yield x = 35

Confidence level = 90%

Find:

Proportion non-conforming

Computation:

Proportion p = x / n

Proportion p = 35 / 200 = 0.175

Non Proportion q = 1 - p

Non Proportion q = 0.825

So,

z value of 90% is 1.64

So,

Proportion non-conforming

p ± [z√pq/n]

0.175 ± [1.64√(0.175)(0.825)/200

(0.131) , (0.044)

the answer is 21%.