Twenty-two concrete blocks were sampled and tested for crushing strength in order to estimate the proportion that were sufficiently strong for a certain application. Eighteen of the 22 blocks were Sufficiently strong. Use the small-sample method to construct a 95% confidence interval for the
Proportion of blocks that are sufficiently strong.
A) (0.593, 0.945)
B) (0.657, 0.979)
C) (0.633, 0.905)
D) (0.607, 0.931)

Question

Quizplus · Accepted Answer

The sample proportion is 18/22 = 0.818. Using the small-sample method (Wilson score interval or adjusted Wald interval), the 95% confidence interval is calculated, resulting in approximately (0.607, 0.931).

Twenty-Two Concrete Blocks Were Sampled and Tested for Crushing Strength