BENCHHMARK

Aptitude Solved Problems

Questions :

1. Certain sum becomes 2 times itself at compound interest in 4 years. In how many years it becomes 8 times?

2. A man can row 6 Km / hr in still water. If the velocity of the current is 3 Km / hr and it takes him 4 hours to row to a place and come back. How far is the place?

3. Two employees M and N are paid a total of Rs. 550 per week by their employer. If M is paid 120 percent of the sum paid to N, how much is N paid per week?

Answers :

1. 12 years

2. 9 km

3. Rs. 250

1. Explanation:

Amount = Principal * ( 1 + ( Rate / 100 ))n
P * ( 1 + ( R/100 ) )4 = 2P
(1 + ( R / 100 ) )4 = 2 ………. ( 1 )
Let P(1 + ( R / 100 ) )n = 8P
(1 + ( R / 100 ) )n = 8
(1 + ( R / 100 ) )n = 23 …………… ( 2 )
Equating ( 1 ) and ( 2 )
23 = [ (1 + ( R / 100 ) )4]3
23 = (1 + ( R / 100 ) )12
(1 + ( R / 100 ) )n = (1 + ( R / 100 ) )12
n = 12 years

∴ Number of years = 12 years

2. Explanation:

Man′s rate down stream = 6 + 3
= 9 km / hr
Man′s rate upstream = 6 – 3
= 3 km / hr
Let the required distance be x km
Distance / Speed = time
( x / 9 ) + ( x / 3 ) = 4
( x + 3x ) / 9 = 4
x + 3x = 4 * 9
4x = 36
x = 36 / 4
∴ x = 9 km

∴ Required distance = 9 km

3. Explanation:

Let the amount paid to M per week = a
The amount paid to N per week = b
Then a + b = Rs. 550
But a = 120% of b
= 120b / 100
= 12b / 10
( 12b / 10 ) + b = 550
b * [ ( 12 / 10 ) + 1 ] = 550
b * ( ( 12 + 10 ) / 10 ) = 550
b * ( 22 / 10 ) = 550
22b = 550 * 10
= 5500
b = 5500 / 22
= 500 / 2
= Rs. 250

∴ The amount paid to N per week = Rs. 250