Question: On certain road 10% of the motorists exceed the posted speed limit and receive speeding tickets, but 20% 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?

1. 10.5%
2. 12.5%
3. 15%
4. 22%
5. 30%

“On certain road 10% of the motorists exceed the posted speed limit and receive speeding tickets, but 20% 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?”- is a topic of the GMAT Quantitative reasoning section of GMAT.
This question has been taken from the book “GMAT Official Guide Quantitative Review”. To solve GMAT Problem Solving questions a student must have knowledge about a good amount of qualitative skills. The GMAT Quant topic in the problem-solving part requires calculative mathematical problems that should be solved with proper mathematical knowledge.

Answer:

Approach Solution 1:

Say there are 100 motorists.
{# of motorists who exceed speed and receive tickets} + {#of motorists who exceed speed and don’t receive tickets} = {Total # of motorists who exceed speed}
Given: {# of motorists who exceed speed} = x
Then 0.2x = {# of motorists who exceed speed and don’t receive tickets}
10 + 0.2x = x
x = 12.5

Correct option: B

Approach Solution 2:

On a certain road, 10% of the motorists exceed the posted speed limit and receive speeding tickets,
10% of the total motorists exceed speed limit and get tickets but 20% of the motorists who exceed the posted speed limit do not receive speeding tickets.
20% who exceed the speed limit do not get tickets. Then 80% who exceed the speed limit must be getting tickets.
What percent of the motorists on the road exceed the posted speed limit?
So 10% of the total motorists = 80% of those who exceed speed limit
So those who exceed speed limits are 1/8 = 12.5% of the motorists

Correct option: B

Suggested GMAT Quant Questions:

• If k is an Integer and 2 < k < 7, for How Many Different Values of k is There a Triangle With Sides of Lengths 2, 7, and k? GMAT problem solving
• How many factors does 36^2 have? GMAT problem solving
• A number when divided successively by 4 and 5 leaves remainder 1 and 4 respectively GMAT problem solving
• Walking at 6/7 th of his usual speed, a man is 25 min too late GMAT problem solving
• The hexagon ABCDEF is regular. That means all its sides are the same length and all its interior angles are the same size. GMAT problem solving
• y varies directly as x and when x = 6, y = 24. What is the value of y, when x = 5? GMAT problem solving
• An Inlet Pipe can Fill in an Empty Cistern in 30 minutes Whereas a leak in the Bottom of the Cistern can Empty a Filled Tank in 40 minutes GMAT problem solving
• A milkman cheats his customers by adding water to the milk he sells GMAT problem solving
• if 80 lamps can be lighted, 5 hours per day for 10 days for $21.25, then the number of lamps, GMAT problem solving
• Few of the corporate contributions to the earthquake relief fund, aside from Pterocom GMAT problem solving
• The product of the first 10 prime numbers is closest to which of the following? GMAT problem solving
• There is a 120 liter mixture of alcohol and water. The ratio of alcohol to water is 7 : 5 GMAT problem solving
• An equilateral triangle ABC is inscribed in square ADEF, forming three right triangles GMAT problem solving
• A Furniture Store Sells Only Two Models of Desks, Model A and Model B. The Selling Price of Model A is $120 GMAT problem solving
• A contractor combined x tons of a gravel mixture that contained 10 percent gravel G GMAT problem solving
• There are 100 Apples in a Bag of which 98% are Green and Rest are Red GMAT problem solving
• How many litres of a 90% solution of concentrated acid needs to be mixed with a 75% solution GMAT problem solving
• Jug Contains Water And Orange Juice In The Ratio 5:7 . Another Jug Contains Water And Orange J GMAT problem solving
• The number of ways in which 8 different flowers can be seated to form a garland so that 4 particular flowers are never separated GMAT problem solving
• A train travels from Albany to Syracuse, a distance of 120 miles, at an average rate of 50 miles per hour GMAT problem solving