Question

A recent survey of post-secondary education students revealed that 70% own an iPhone. Suppose a random sample of 240 post-secondary students is taken. What is the probability that less than 162 students in the sample own an iPhone?

a) 0.8023

b) 0.2033

c) 0.1977

d) 0.7967

Answer 1

Solution :

Given that,

p = 70% = 0.70

q = 1 - p = 1 - 0

n = 240

Using binomial distribution,

= n * p = 240 * 0.70 = 168

= n * p * q = 240 * 0.70 * 0.30 = 7.0993

Using continuity correction ,

P(x < 161.5) = P((x - ) / < (161.5 - 168) / 7.1)

= P(z < -0.85)

= 0.1977

Probability = 0.1977