Quantitative Aptitude - Arithmetic Ability Questions

Given A,B,C can complete a work in 15,20 and 30 respectively.

The total work is given by the LCM of 15, 20, 30 i.e, 60.

A's 1 day work = 60/15 = 4 units

B's 1 day work = 60/20 = 3 units

C's 1 day work = 60/30 = 2 units

(A + B + C) worked for 2 days = (4 + 3 + 2) 2 = 18 units

 Let B + C worked for x days = (3 + 2) x = 5x units

C worked for 2 days = 2 x 2 = 4 units

Then, 18 + 5x + 4 = 60

22 + 5x = 60

5x = 38

x = 7.6

Therefore, total number of days taken to complete the work = 2 + 7.6 + 2 = 11.6 = 11 3/5 days.

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.

Given expression = 0.2×0.2×0.010.1×0.1×0.02=0.04+0.010.01+0.02=0.050.03=53

From the given data,

K's profit : L's profit = 7x x 11 : 9x x 7

= 11:9

Therefore, L's profit = 9 x 2460/20 =  Rs. 1107

Watson bought the book for Rs. 240 and sold to Johny at a profit of 50%.

S.P = C.P(1 + P%/100)

=> S.P for Watson = C.P for Johny = 240(1 + 50/100) = 240 x 1.5 = Rs. 360

Let Johny quoted the marked price of the book as Rs. M

We know, SP = M.P(1 - Discount(%)/100)

Here discount = 10% to Shekar,

S.P for Johny = M(1 - 10/100) = 0.9M

But Johny want to earn 25% profit,

=> S.P = C.P(1 + P%/100)

=> 0.9M = 360(1 + 25/100)

=> M = (360x1.25)/0.9

=> M = Rs. 500

Therefore, Johny should quote Rs. 500 as the marked price of the book to get 25% profit and allowing 10% discount to Shekar.

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.

Since the compound interest is taken here,

 PW1+51002=1764

=> PW = 1600