31) The number of times 2 is used while writing the numbers from 1 to 100 is
a) 19
b) 18
c) 21
d) 20
32) 3x + 2y = 12 and xy= 6, then the value of 9x2 + 4y2 is
a) 76
b) 80
c) 72
d) 74
33) Volumes of two cubes are in the ratio 8 : 27. Ratio of their surface area is
a) 2 : 3
b) 3 : 2
c) 4 : 9
d) 9 : 4
34) The largest sphere is curved out from a cube of side 21 cm. The volume of remaining part is
a) 4770 cm3
b) 4410 cm3
c) 4370 cm3
d) None of these
35) If a + b= 8, a – b = 4, then a2 + b2 is equal to
a) 20
b) 40
c) 10
d) 30
36) If 7n + 9 >100 and n is an integer, then smallest possible value of n is
a) 13
b) 12
c) 14
d) 15
37) The sum of a natural number and its square equal the product of the first three prime numbers. The number is
a) 2
b) 3
c) 5
d) 6
38) If ( x+ 7954 x 7956) be a square number ,Then the value of x is
a) 1
b) 16
c) 9
d) 4
39) HCF of x2 – y2 and x3 – y3 is
a) x- y
b) x3 – y3
c) (x2 – y2)
d) (x + y)( x2+xy +y2)
40) The cost price of 18 articles is equal to the selling price of 15 articles. The gain is
a) 25%
b) 20%
c) 18%
d) 15%