Problem Solving

On a certain road 10 percent of the motorists exceed the posted speed limit and receive speeding tickets, but 20 percent of the motorists who exceed the posted speed limit do not receive speeding tickets. What percent of the motorists on the road exceed the posted speed limit?
A) 10.5%
B) 12.5%
C) 15%
D) 22%
E) 30%

OA is B

On a certain road 10 percent of the motorists exceed the posted speed limit and receive speeding tickets, but 20 percent of the motorists who exceed the posted speed limit do not receive speeding tickets. What percent of the motorists on the road exceed the posted speed limit?

let x be total nos of motorists

.1x get tickets

let y be nos of motorists who exceed speed limt

so .2y do not get tickets & .8y get tickets

so .1x=.8y

y/x = 1/8

=12.5 %