Inactive Tutor answered 04/14/20
We can use the binomial formula to solve this probability question. The probability for the first outcome, that is smartphone use, is given as 0.49. Therefore, the other probability would become
Pno−smartphone=1−0.49=0.51
We can calculate the probability as shown below.
P(exactly 5 smart phone)=7C5 × 0.495 × 0.517-5
= 21 × 0.028× 0.2601
=0.1530