Question

A sample of 51 observations will be taken from an infinite population. The population proportion equals 0.85. The probability that the sample proportion will be between 0.9115 and 0.946 is
a. 0.8633

b. 0.6900

c. 0.0819

d. 0.0345

Answer 1

Answer:

c. 0.0819

Explanation:

The mean = 0.85

standard error of the proportion is:     sp = sqrt(pq/n)

= sqrt ((.85)(0.15) / 51) = 0.05

P(0.9115 < X < 0.946) = P( (0.9115 - 0.85) / 0.05 < z < (0.946 - 0.85) / 0.05 )

= P(1.23 < z < 1.92)

= P(z < 1.92) - P(z < 1.23) = 0.0819