PROBLEM SOLVING Objective – The questions in problem solving are specifically designed to measure your ability to reason quantitatively and solve the problem. There are 18-19 problem solving questions with 5 answer choices each. You need to use basic concepts of maths and the information provided in the question to choose the correct answer. GMAT quant questions are usually not as difficult as compared to those in Indian aptitude exam.
Example – A train is going at 2/3 of its usual speed and it takes an extra 30 minutes to reach its destination. What is its usual time to cover the same distance?
A. 30 minutes
B. 45 minutes
C. 60 minutes
D. 75 minutes
E. 90 minutes
Solve this question in less than 10 seconds with the use of Inverse relationship concept between changing speed and time. Here, the concept states that if speed decreases by 1/x then the time has to be increased by 1/x correspondingly.
The train is going at 2/3rd of its original speed which means that there is a decrease of ⅓ in its speed. So, a corresponding increase of ⅓-1 =⅓ should be there in the final time taken. From this question, we come to know that the train takes an extra 30 minutes time to cover the same distance. It’s just an increase of ½ in the original time nothing else. Therefore, if ½ of the original time is 30 minutes then the original time has to be 30*2=60 minutes.