Quantitative Aptitude Questions and Answers With Explanation (Practice set 21)

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Q1:
The average age of 8 men is increased by years when two of them whose ages are 21 years and 23 years are replaced by two new men. The average age of the two new men is :

A) 20 B) 30
C) 40 D) 50

Q2:
The H.C.F and L.C.M of two numbers are 11 and 385 respectively. If one number lies between 75 and 125, then that number is

A) 77 B) 88
C) 99 D) 110

Q3:
In a zoo, there are rabbits and pigeons. If heads are counted, there are 340 heads and if legs are counted there are 1060 legs. How many pigeons are there?

A) 120 B) 150
C) 170 D) 180

Q4:
Two dice are thrown together. What is the probability that the sum of the number on the two faces is divided by 4 or 6?

A) 7/18 B) 14/35
C) 8/18 D) 7/35

Q5:
Find the next number in the series 125, 80, 45, 20,...

A) 5 B) 15
C) -5 D) 10

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Quantitative Aptitude Questions and Answers With Explanation (Practice set 20)

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Q6:
92613 x 62742241 = ? + 89
Find the value of '?'

A) 166251 B) 166259
C) 166252 D) 166253

Q7:
One side of a rectangular field is 15m and one of its diagonal is 17m. Find the area of the field?

A) 110 B) 120
C) 130 D) 140

Q8:
The profit earned by selling an article for Rs 900 is double the loss incurred when the same article is sold for Rs.490. At what price should the article be sold to make a 25% profit?

A) 715 B) 469
C) 400 D) 750

Q9:
In a two-digit number, the digit in the unit's place is more than twice the digit in ten's place by 1. If the digits in the unit's place and the ten's place are interchanged, the difference between the newly formed number and the original number is less than the original number by 1. What is the original number?

A) 35 B) 36
C) 37 D) 39


Q10:
Three numbers are in the ratio  1: 2 : 3  and their H.C.F is 12. The numbers are

A) 4, 8, 12 B) 5, 10, 15
C) 10, 20, 30 D) 12, 24, 36

ANSWERS WITH EXPLANATION


Answer1: B) 30
Explanation:
Total age increased = (8 * 2) years = 16 years.
Sum of ages of two new men = (21 + 23 + 16) years = 60 years
The average age of two new men = (60/2) years = 30 years.

Answer2: A) 77
Explanation:
Product of numbers = 11 x 385 = 4235
Let the numbers be 11a and 11b . Then , 11a x 11b = 4235  =>  ab = 35
Now, co-primes with product  35 are (1,35) and (5,7)
So, the numbers are ( 11 x 1, 11 x 35)  and (11 x 5, 11 x 7)
Since one number lies 75 and 125, the suitable pair is  (55,77)
Hence, required number = 77

Answer3: B) 150
Explanation:
Suppose there are all the pigeons then the total no of heads is 340 and the total no of legs is 680. 
Now, since 380 (1060-680) legs are extra, it means there will be 190 (380/2) rabbits. As we know a rabbit has two extra legs than that of a pigeon.
Therefore,  number of rabbits =190
and number of pigeons = 340- 190 = 150

Answer4: A) 7/18
Explanation:
Clearly, n(S) = 6 x 6 = 36
Let E be the event that the sum of the numbers on the two faces is divided by 4 or 6.
Then,E = {(1,3),(1,5),(2,2),(2,4),(2,6),(3,1),(3,3),(3,5),(4,2),(4,4),(5,1),(5,3),(6,2),(6,6)}
n(E) = 14.
Hence, P(E) = n(E)/n(S) = 14/36 = 7/18

Answer5: A) 5
Explanation:
The pattern is -45, -35, -25, -15
The next number = 20-15= 5

Answer6: C) 166252
Explanation:
Given 92613 x 62742241 = ? + 89
Using unit digit method,
On LHS,
1 x 1 x 1 = 1
sqrt of last digit 1 => it must end with either 9 or 1
so now
1 x 1 = 1
1 x 9 = 9
On RHS,
? + 89
=> ? = ...1 - 89 = last digit is 11- 9 = 2
or
=> ? = ...9 - 89 = last digit is 9 - 9 = 0
Here in the options last digit 2 is option C.

Answer7: B) 120
Explanation:
Other side = [(17 x 17) - (15 x 15)] = (289 - 225) = 8m
Area = 15 x 8 =120 sq. m

Answer8: D) 750
Explanation:
Let C.P be Rs. x 
900 - x = 2(x - 450)     => x = Rs.600   
C.P = 600 gain required is 25% 
S.P = [(100+25) x 600] / 100 = Rs.750

Answer9: C) 37
Explanation:
Let the ten's digit be x. Then, unit's digit = 2x + 1.
[10x + (2x + 1)] - [{10 (2x + 1) + x} - {10x + (2x + 1)}] = 1
<=> (12x + 1) - (9x + 9) = 1 <=> 3x = 9, x =  3.
So, ten's digit = 3 and unit's digit = 7. Hence, original number = 37.

Answer10: D) 12, 24, 36
Explanation:
Let the required numbers be x, 2x, 3x.   Then, their H.C.F =x. so, x= 12
Therefore, The numbers are 12, 24, 36.

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