Question

A recent survey found that 71% of senior adults wear glasses for driving. In a group of 20 senior adults, how like that no more than 10 wear glasses for driving?

a.95.2%

b.1.7%

c.3.1%

d.4.8%

Answer 1

c. 3.1%

Explanation:

given that a recent survey found that 71% of senior adults wear glasses for driving.

If X is the number of senior adults, who like that wear glasses for driving

then X is binomial with n = 20 and p = 0.71

(since each person is independent of the other)

Probability that no more than 10 wear glasses for driving

=
`P(X\leq 10)\\=F(10)\\= \Sigma_0^(20) 20Cr (0.71)^r (0.39)^(20-r) \\=0.03848`

Convert into percent as

= 3.8%

Approximately 3.1% is right.