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?
17%
19%
36%
70%

Answer 1

Answer:

The correct answer is B. 17%

Step-by-step explanation

• Use the formula for the conditional probability:    

Pr(A/B) = Pr(A ∩ B) ÷ PrB

Consider such events

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

B -  a senior has a driver’s license,

then Pr(A ∩ B)  = 0.14

Pr(B) = 0.84

and

Pr(A/B) = 0.14÷0.84 = 1/6 ≈ 0.16666

In percent this is nearly 17%.

                   

Answer 2

Answer:

B. 17%

Step-by-step explanation:

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