Quantitative Aptitude - Arithmetic Ability Questions

Given Lasya can do a work in 16 days.

Time taken by Rashmi = n days

=> (12 x 20)/(20 - 12) = (12 x 20)/n

=> n= 30 days.

Required ratio of efficiencies of Rashmi and Lasya = 1/30  ::  1/16  = 8 : 15.

142 x 142 x 11260.25

=> 142 x 142 x 135.5 = 568

G.C.D is nothing but H.C.F

Given numbers are 1.08 , 0.36 and 0.90

we can take as 108, 36 and 90 

Then required H.C.F is 18.

Therefore, H.C.F of given numbers is 0.18.

In a family with 2 children there are four possibilities:
1) the first child is a boy and the second child is a boy (bb)
2) the first child is a boy and the second child is a girl (bg)
3) the first child is a girl and the second child is a boy (gb)
4) the first child is a girl and the second child is a girl (gg)

But already given that one child is boy. So we have three possibilities of (bb)(bg)(gb).
n(E)= both are boys=BB=1
n(S)= 3
Required probability P = n(E)/n(S) = 1/3.

Let the number of boys = b

Let the number of girls = g

From the given data,

81b + 83g = 81.8(b + g)

81.8b - 81b = 83g - 81.8g

0.8b = 1.2g

b/g = 1.2/0.8 = 12/8 = 3/2

=> g : b = 2 : 3

Hence, ratio between the number of girls to the number of boys = 2 : 3.

Total balls = 40

Red balls = 18

Let green balls are x

Then, (18/40) × (