Question

A survey of the 12th grade students at Gaffigan High School found that 84% of the seniors have their driver’s licenses, 16% of seniors take the bus every day to school, and 14% of the seniors have driver’s licenses and take the bus to school every day.

To the nearest whole percent, what is the probability that a senior takes the bus to school every day, given that he or she has a driver’s license?

19%
17%
36%
70%

Answer 1

B on Edge

Explanation:

Trust me

Answer 2

Use the formula for the conditional probability:

`Pr(A|B)=(Pr(A\cap B))/(Pr B).`

Consider such events

A - a senior takes the bus to school every day;

B - a senior has a driver’s license,

then

`Pr(A\cap B)=0.14`,

`Pr(B)=0.84`

and

`Pr(A|B)=(0.14)/(0.84) =(1)/(6)\approx 0.16666.`

In percent this is nearly 17%.

Answer: correct choice is B.