GMAT math thinking skills 6

 

Many students get stumped when they see a math problem. They do not know how to start and how to proceed. They read the question many times, trying to spot the clues. Sometimes the clues are hidden in the questions. Some times they are explicit.  

If you fall into this category.. Fear not.. There is an approach which can help you approach  math questions better.

Follow this 3 step problem solving process.

1. Collect the data given

2. Diagram the problem.

Break the question into segments. Do not read the entire question. After reading a segment, jot down the data on paper. Represent the data in the form of a table or any diagram.

3. Recall a math formula/concept which you can apply and solve

Let us use this approach and solve this problem

Step 1: Collect the data given

Data: 

1. 60 people are there
2. No two rank the same
3. (3/5) of 60 ranked vanilla last = (3/5)x 60 =36
4. (1/10) of 60 ranked vanilla before chocolate = (1/10)x 60 =6
5. (1/3) of 60 ranked vanilla before strawberry = (1/3)x 60 =20

Step 2. Diagram the problem.

Lets diagram the data. I have ranked the data 1,2,3

36 people ranked V(vanilla) last

6 people ranked V before C(chocolate). There are two cases here.  V is ranked 1 or 2.

20 people ranked V before S(Strawberry). There are two cases here. V is ranked 1 or 2.

If you observe 

Out of 60, 36 people ranked V last. Balance  = 60-36 =24 

There are 24 people..

6 people marked V before C (group 1) and 20 people marked V before S(group 2). Hence there should be some people common to both groups ( as 20+6 is not 24) These people should have ranked V first

3. Recall a math formula/concept which you can apply.

Set theory can be used to represent data which is common in two groups

20 is group 1.. 6 is group 2. X represents the number of people, who are common to both groups.

Formula: A union B =A+B-A intersection B

24 =20+6-x

x= 2

Follow this 3 step process. and remember to diagram data. 

This approach makes life easier in the GMAT.