Mettl Quantitative Aptitude 5

Question 1

The speed of a boat in still water is 15 km/h. The current speed is 3 km/h. What is the ratio of upstream to downstream speed?

Accepted Answer

2:3

Answer

Upstream = 12 km/h, downstream = 18 km/h; ratio = 12:18 = 2:3.

Question 2

A rectangle has a perimeter of 56 cm. If its length is 3 times its width, what is the area?

Accepted Answer

147 cm²

Answer

2(l+w)=56 → l+w=28; l=3w → 4w=28 → w=7, l=21; area=21×7=147 cm².

Question 3

A sum of money doubles itself in 8 years at simple interest. What is the annual rate of interest?

Accepted Answer

12.5%

Answer

SI = P in 8 years; P = P×R×8/100 → R = 100/8 = 12.5%.

Question 4

In how many ways can 4 books be arranged on a shelf from a collection of 7 different books?

Accepted Answer

840

Answer

This is a permutation: P(7,4) = 7!/(7−4)! = 7×6×5×4 = 840.

Question 5

A man spends 30% of his salary on rent, 20% on food, and saves the rest. If he saves $2,100, what is his salary?

Accepted Answer

$4,200

Answer

He saves 50% of salary; 0.50 × salary = $2,100 → salary = $4,200.

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