NUMBER SYSTEM : Quantitative Aptitude series-8

Welcome to Coaching Genie's series-8 of Quantitative Aptitude. The Best free IBPS PO Clerk coaching.

This is a series on NUMBER SYSTEM.

71.The smallest number, which when subtracted from the sum of squares of 12 and 14 gives a perfect square, is
a)6
b)18
c)24
d)16
e)8

Ans. 12 + 14² = 340
while 18² = 324
so the difference 340 - 324 = 16

 

72.The 7/9 th of a number exceeds its 3/4 th by 10. Find the number?
a)280
b)420
c)360
d)580
e)450

Ans. Let the number be y.
so 7/9 y - 3/4 y = 10
so 28y - 27y = 10 * 36
so y = 360

 

73.Three books and two erasers cost Rs. 42 and four erasers and a book cost Rs. 24. Find the cost of a book?
a)18
b)12
c)20
d)15
e)22

Ans. Let the book be x and eraser be y
so 3x + 2y = 42---------(1)
and x + 4y = 24---------(2)
(1)*2 gives
6x + 4y = 84-------------(3)
(3) - (2) gives
5x = 60
x = 60/5 = 12

 

74.Sum of two numbers is 1/2 nd of 1/3 rd of 60 and their product is 1/7 th of 1/5 th of 840. Find 3/2 nd of the difference between them ?
a)2
b)1
c)4
d)3
e)5

Ans.Let the numbers be a and b.
so a + b = 1/2 * 1/3 * 60 = 10
a + b = 10 --------------(1)
a * b = 1/7 * 1/5 * 840 = 24
a * b = 24 ---------------(2)
Eqn (1) gives
b = 10 - a ----------------(3)
putting (3) in (2)
a * (10 - a) = 24
10a - a² = 24
a² - 10a + 24 = 0
solving gives
(x - 6)(x - 4) = 0
x = 6 and 4
So the numbers are 6 and 4
3/2 of difference = 3/2 * (6-4) = 3/2 * 2 = 3

75.When 5 is added to a number and the sum is multiplied by 6, the result is same as when 16 is multiplied by 7 and 8 is added to the product. The number is _____
a)25
b)18
c)23
d)15
e)28

Ans. Let the number be a
so (a + 5) * 6 = (16 * 7 ) + 8
gives 6a + 30 = 120
6a = 90
so a = 90/6 = 15

 

76.The number of employees in a company are 2800 more than 1/5 th of it. Find the total number of employees?
a)5600
b)3500
c)4200
d)2600
e)1900

Ans. Let the total number of employees be T
so 1/5T + 2800 = T
4/5T = 2800
T = 3500

 

77.The total mangoes in three baskets P ,Q and R are 1120.P contains four times that of Q. Q contains three times that of R. P contains how much more mangoes than R?
a)550
b)660
c)770
d)880
e)990 

Ans. So P + Q + R = 1120 ---------(1)
P = 4Q --------------(2)
Q = 3R --------------(3)
putting (3) and (2) in (1)
4*(3R) + 3R + R =1120
16R =1120
R = 70
so Q = 3*70 = 210
P = 4*210 = 840
so difference P - R = 840 - 70 = 770

 

78.The amount that Rahul had was Rs.820 more than 6/7 th of 1/12 th of 588.Find the amount?
a)862
b)848
c)854
d)826
e)884

Ans.(588 * 6/7 * 1/12) + 820 = 42 + 820 = 862

 

79.Each person in a group contributed as many paise as the number of persons in the group.An amount of Rs.17 is added to it to make the total collection as Rs81.How many persons are there in the group?
a)65
b)72
c)80
d)94
e)98

Ans.Let the number of people in the group be a.
Converting Rs17 and Rs.81 to paise gives 1700 and 8100
so a² + 1700 = 8100
a² = 8100 - 1700 = 6400
a = 80 

 

80.The 6/7 th of 140% of a number is 367 more than 497.Find the number?
a)840
b)630
c)942
d)588
e)720

Ans.Let the number be y.
So, 6/7 * 140/100 * y = 367 + 497
6/5 y = 864
y = 864*5/6 = 720