Question

A poll shows that Presidential approval rating is 42% for the population. If 275 people are surveyed, what is the probability that over 50% approve of the President?

Write the probability question in terms of the random variable, in terms of z, and round off the probability to 4 decimal places.

Answer 1

Solution

Given that,

p = 0.42

1 - p = 1-0.42=0.58

n = 275

= p =0.42

=  [p( 1 - p ) / n] = [(0.42*0.58) /275 ] = 0.0298

P( >0.50 ) = 1 - P( < 0.50)

= 1 - P(( - ) / < (0.50 -0.42) / 0.0298)

= 1 - P(z <2.68 )

Using z table

= 1 -0.9963

=0.0037

probability=0.0037