# Aptitude [3i Infotech Placement]: Sample Questions 14 - 16 of 76

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## Question 14

Aptitude
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### Write in Short

City A՚s population is 68000, decreasing at a rate of 80 people per year. City B having population 42000 is increasing at a rate of 120 people per year. In how many years both the cities will have same population?

### Explanation

City A՚s population is 68000, decreasing at a rate of 80 people per year.

City B՚s population is 42000, increasing at a rate of 120 people per year.

Let in p years population of both cities be same.

So,

So, in 130 years population of both cities will be same.

## Question 15

Aptitude

### Question

MCQ▾

What is the smallest number by which 2880 must be divided in order to make it into a perfect square?

Choice (4)

a.

3

b.

6

c.

4

d.

5

d.

### Explanation

Factors of 2880 are

We can clearly see from the factors that we need to multiply the number by 5 to make it a perfect square.

## Question 16

Aptitude

### Question

MCQ▾

Two trains move in the same direction at 50 kmph and 32 kmph respectively. A man in the slower train observes the 15 seconds elapse before the faster train completely passes by him. What is the length of faster train?

Choice (4)

a.

50m

b.

100m

c.

120m

d.

75m

d.

### Explanation

Two trains are moving in the same direction with speed 50 kmph and 32 kmph.

So, net speed

A man in the slower train observes the 15 seconds elapse before the faster train completely passes by him.

We are asked to find the length of the faster train. Let it be x km.

So,

So, length of the train is 75 m.

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