Quantitative Aptitude - Arithmetic Ability Questions

Given R + S + M + D = 76

=> R+7 : S+7 : M+7 : D+7 = 7:6:5:8

=> Let the ratio = x

=> M+7 = 5x

=> M = 5x-7

=> R = 7x-7

=> S = 6x-7

=> D = 8x-7

=> R + S + M + D = 76

=> 7x-7 + 6x-7 + 5x-7 + 8x-7 = 76

=> 26x - 28 = 76

=> 26x = 104

=> x = 4

=> Mahesh's present age = 5x-7 = 20 - 7 = 13 years.

Distance to be covered = πD = 40π km 

Relative speed of bikers = 16 + 14 = 30 kmph.

Now, time=distancespeed =  40π30 = 4.18 hrs.

Let the number of buffaoes be x and number of ducks be y.

Then 4x + 2y = 2(x + y) + 24  

=> 2x = 24

=> x = 12.

Let their edges be a and b. Then,

a3/b3 = 1/27 (or) (a/b)3 = (1/3)3 (or) (a/b) = (1/3).

\Ratio of their surface area = 6a2/6b2 = a2/b2 = (a/b)2 = 1/9, i.e. 1:9.

The ratio of their investments:
50000x36 : 80000x30 = 3 : 4
Simran's share of profit = (24500x3/7) = Rs.10,500.

The number of arrangements of 4 different digits taken 4 at a time is given by 4P4 = 4! = 24.All the four digits will occur equal number of times at each of the position,namely ones,tens,hundreds,thousands.

Thus,each digit will occur 24/4 = 6 times in each of the position.The sum of digits in one's position will be 6 x (1+3+5+7) = 96.Similar is the case in ten's,hundred's and thousand's places.

Therefore,the sum will be 96 + 96 x 10 + 96 x 100 + 96 x 100 = 106656

By investing Rs 128, income derived = Rs. 16

By investing Rs. 100, income derived =Rs. (16/128*100)  = Rs.12.5

Interest obtained  = 12.5%