GRE Numeric Entry Sample Questions

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1. Question :

The average age of the 5 members of a family is 25 years. The age of the youngest member is 5 years. What was the average age of the members of the family just before the youngest member was born?

Correct Answer:

25 years

Explanation:

Sum of ages of 5 members=25*5

=125

The sum of ages of five members increased by 25 years in the last five years.

Five years ago the sum of the ages was=125 – 25=100.

Five years back there were 4 members in the family.

Hence, average age five years back=100/4

=25 years.

2. Question :

The odds in favour of an event are 4:5. In how many chances out of 36 shall the event occur?

Correct Answer:

16

Explanation:

Odds n favour of the event are 4:5

Probability of occurrence of the event=4/(4+5)

=4/9

If the chances are 36, the number of chances of the occurrence of the event are 36/9*4

=4*4=16

3. Question:

If two pipes work simultaneously, the reservoir fills in 12 hours. One pipe fills the reservoir 10 hours faster than the other does. How many hours does the faster pipe take to fill the reservoir alone?

Correct Answer:

20

Explanation:

Let the two pipes be F and S where F is the faster pipe and S is the slower pipe.

Let S take x hours to fill the tank and F will take (x-10) hours.

Work done by S in one hour=1/x

Work done by F n one hour=1/(x-10)

Work done by F and S working together in one hour=1/12

1/x+1/(x-10)=1/12

(x-10+x)/[x(x-10)]=1/12

12(2x-10)=x(x-10)

24x-120=x^2-10x

x^2-34x+120=0

x^2-30x-4x+120=0

x(x-30)-4(x-30)=0

x=4,30

x cannot be 4 since x>10

x=30

The faster pipe takes 30-10=20 hours to fill the reservoir.

GRE Numeric Entry Sample Questions

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