Question

a survey report show that in locality 60 percent of families earning more than rs 15000 own a car .if sample is 18 families in this category find probability exactly 12 than own a car

Answer 1

Let $X=$ the number of families own a car: $X\sim Bin (n, p).$

Given $n=18, p=0.6$

$$P(X=12)=\dbinom{18}{12}(0.6)^{12}(1-0.6)^{18-12}$$

$$=0.165518488721424384\approx0.1655$$