Question

A Pew Research report indicated that 73% of teenagers aged 13-17 own smartphones. A random sample of 150 teenager is drawn. (If using TI-84 plus, show steps)

a. Find the mean ??̅ .

b. Find the standard deviation ??̅.

c. Find the probability that more than 70% of the sampled teenagers won a smartphone.

Answer 1

p = 0.73

n = 150

a) = p = 0.73

b) = sqrt(p(1 - p)/n)

           = sqrt(0.73(1 - 0.73)/150)

           = 0.0362

c) P( > 0.7)

= P(Z > -0.83)

= 1 - P(Z < -0.83)

= 1 - 0.2033

= 0.7967