Question

the manufacturer of aspirin claims that the proportion of headache sufferers who get relief with thin just to ask Grace is 53% what is the probability in a random sample of 400 headache stuff for less than 50%

Answer 1

Solution

Given that,

p = 53%=0.53

1 - p = 1 - 0.53=0.47

n = 400

= p =0.53

=  [p ( 1 - p ) / n] =   [(0.53*0.47) / 400 ] = 0.025

P( <0.50 ) =

= P[( - ) / < (0.50-0.53) /0.025 ]

= P(z <-1.2 )

Using z table,   

probability =0.1151