Question

The proportion of left hand dpeople in the general population is about 40%.Suppose a random sample. of 36 people is observed.

What is the probability of obtaining 20 or less left handed people in your sample of 36?

Answer 1

Given : n=36 , p=0.40

Here , X has binomial distribution with parameter n and p.

Now , np=36*0.40=14.4>10 and n(1-p)=36*(1-0.40)=21.6>10

Therefore , use the normal approximation ,

Now ,

; From the standard normal probability distribution table

Therefore , the

probability of obtaining 20 or less left handed people in your sample of 36 is 0.9719