Quantitative Aptitude - Arithmetic Ability Questions

Q:

The value of a machine depreciates at the rate of 10% every year. It was purchased 3 years ago. If its present value is Rs. 8,748, its purchase price was ?

A) Rs.14,000 B) Rs.12,000
C) Rs. 12,800 D) Rs. 15,000
 
Answer & Explanation Answer: B) Rs.12,000

Explanation:

We have P = 8748, R = -10 and n = 3
Therefore, the purchase price of the machine
= P1+R100n= 87481-101003
= 8748 x (100/90) x (100/90) x (100/90)
= 12,000.

 

Therefore, the purchase price of the machine was Rs. 12,000.

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Filed Under: Percentage
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7 10069
Q:

Arun, Kamal and Vinay invested Rs.8000, Rs.4000 and Rs. 8000 respectively in a business. Arun left after six months. If after eight months, there was a gain of Rs. 4005, then what will be the share of Kamal?

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Subject: Partnership

59 10067
Q:

When Raj Tarun was born, his father was 32 years older than his brother and his mother was 25 years older than his sister. If Raj Tarun's brother is 6 years older than Raj Tarun and his mother is 3 years younger than his father, how old was Raj Tarun's sister when Raj Tarun was born ?

A) 5 B) 10
C) 15 D) 8
 
Answer & Explanation Answer: B) 10

Explanation:

Raj Tarun's age = 0 when he was born.
Then, given his brother is 6 years old.
Then his father is 6 + 32 = 38 when Raj Tarun was born
And his mother is 3 years yonger than his father => so his mother was 35 years old when Raj Tarun was born
and his sister is 25 year younger than his mother
so Raj Tarun's sister was 10 years old when Raj Tarun was born.

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Filed Under: Problems on Ages
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12 10051
Q:

A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If the area of the field is 680 sq. feet, how many feet of fencing will be required?

A) 22 B) 44
C) 66 D) 88
 
Answer & Explanation Answer: D) 88

Explanation:

We have: l = 20 ft and lb = 680 sq. ft.So, b = 34 ft.

Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft.

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Filed Under: Area
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3 10051
Q:

Buses start from a bus terminal with a speed of 20 km/hr at intervals of 10 minutes. What is the speed of a man coming from the opposite direction towards the bus terminal if he meets the buses at intervals of 8 minutes?

A) 5 kmph B) 6 kmph
C) 7.5 kmph D) 8 kmph
 
Answer & Explanation Answer: A) 5 kmph

Explanation:

Let p be the speed of man in kmph

According to the given data in the question,

Distance travelled by bus in 10 min with 20 kmph == Distance travelled by man in 8 min with (20 + p) kmph in opposite direction

=> 20 x 10/60 = 8/60 (20 + p)

=> 200 = 160 + 8p

=> p = 40/8 = 5 kmph.

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14 10037
Q:

A train is traveling at 48 kmph . It crosses another train having half of its length , traveling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. What is the length of the platform ?

A) 500 B) 400
C) 360 D) 480
 
Answer & Explanation Answer: B) 400

Explanation:

Speed of train 1 = 48 kmph
Let the length of train 1 = 2x meter

Speed of train 2 = 42 kmph
Length of train 2 = x meter (because it is half of train 1's length)

Distance = 2x + x = 3x
Relative speed= 48+42 = 90 kmph = (90*5/18)  m/s = 25 m/s 


Time = 12 s

Distance/time = speed 

=>3x/12 = 25 (25*12)/3 

Length of the first train = 2x = 200 meter
Time taken to cross the platform= 45 s

Speed of train 1 = 48 kmph = 480/36 = 40/3 m/s

Distance = 200 + y     [where y is the length of the platform] 

x =100m => 200+y = 45* 40/3
y = 400m

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Filed Under: Problems on Trains

13 10035
Q:

If x is chosen at random from the set {1,2,3,4} and y is to be chosen at random from the set {5,6,7}, what is the probability that xy will be even?

A) 1/2 B) 2/3
C) 3/4 D) 4/3
 
Answer & Explanation Answer: B) 2/3

Explanation:
 

S ={(1,5),(1,6),(1,7),(2,5),(2,6),(2,7),(3,5),(3,6),(3,7),(4,5),(4,6),(4,7)}
Total element n(S)=12

xy will be even when even x or y or both will be even.
Events of x, y being even is E.
E ={(1,6),(2,5),(2,6),(2,7),(3,6),(4,5),(4,6),(4,7)}
n(E) = 8

P(E)=n(E)n(S)=812 = 4/3

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Filed Under: Probability

15 10031
Q:

45 men working 9 hours per day dig 40 m deep. How many extra men should be put to dig to a depth of 56 m working 7 hours per day ?

A) 36 B) 61
C) 48 D) 54
 
Answer & Explanation Answer: A) 36

Explanation:

(45 x 9)/40 = (M x 7)/56 => M = 81

=> 81 – 45 = 36

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Filed Under: Time and Work
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6 10022