Question

If a random sample of 100 items is taken from a population in which the proportion of items having a desired attribute is p=0.45, what is the probability that the proportion of successes in the sample will be less than or equal to 0.49

The probability will be ____

Answer 1

Solution:

Given that,

n = 100

=0.45

1 - = 1 -0.45,= 0.55

So,

=   = 0.45

=   ( 1 - ) / n

=   0.45 * 0.55 / 100

=0.0497

= 0.0497

Standard error = 0.0474

P (     0.49 )

P ( -    / ) ( 0.49 - 0.45 /0.0497 )

P ( z    0.04 /0.0497 )

P ( z   0.80 )

Using z table

= 0.7881

Probability = 0.7881