Question

The proportion of eligible voters in the next election who will vote for the incumbent is assumed to be 52.8%. What is the probability that in a random sample of 490 voters, less than 49.2% say they will vote for the incumbent?

Answer 1

Solution

Given that,

p = 0.528

1 - p = 1 - 0.528 = 0.472

n = 490

= p = 0.528

=  [p ( 1 - p ) / n] =   [(0.528 * 0.472) / 490 ] = 0.0226

P( < 0.492)

= P[( - ) / < (0.492 - 0.528) / 0.0226]

= P(z < -1.59)

Using z table,

= 0.0559