Problem Solving

q1: 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 do not receive speeding tickets. What percent of the motorist on that road exceed the posted speed limit?

a. 10.5% b. 12.5% c.15% d. 22% e.30%

Why the answer not e but b

q2: If a 10 percent deposit that has been paid toward the purchase of a certain product is $110, how much remain to be paid?
a. 880 b.900 c.1000 d.1100 e. 1210
Why the answer not 990 but 900 as total is 110/0.1 = 1100, the remain=1100-110=990.

q1 -

10% of all motorists exceed the speed limit and get a ticket

20% of the speeders exceed and do not get a tix. That means that 80% of the speeders do get tickets.

So 10% of all motorists = 80% of the speeders.

10/80 = x/100
80x = 1000
x = 1000/80 = 10/8 = 5/4 = 12.5%

Answer = B

As for Q2, I cannot figure out anyway that it is not $990. If you put 10% down, then you have 90% to go. If 10% = $110, then 9*10% = 90% = $110*9 = $990.

You may want to go back to the source and make sure you copied the question correctly.

-Carrie

and it would be much easier (and follow the rules of the board) if you put just one question in a post.