Question

A manufacturer of aspirin claims that the proportion of headache sufferers who get relief with just two aspirins is 62.6%. What is the probability that in a random sample of 450 headache sufferers, less than 59.1% obtain relief?

Answer 1

Solution

Given that,

p = 0.626

1 - p = 1 - 0.626 = 0.374

n = 450

= p = 0.626

=  [p ( 1 - p ) / n] =   [(0.626 * 0.374) / 450 ] = 0.0228

P( < 0.591)

= P[( - ) / < (0.591 - 0.626) / 0.0228]

= P(z < -1.54)

Using z table,

= 0.0618