Aptitude and Reasoning 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.

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

Milk in 1-litre mixture of A = 4/7 litre. 

Milk in 1-litre mixture of B = 2/5 litre. 

Milk in 1-litre mixture of C = 1/2 litre.

By rule of alligation we have required ratio X:Y   

   X                  :                 Y  

  4/7                                2/5  

           \                      /

              (Mean ratio)
                   (1/2) 

           /                      \

 (1/2 – 2/5)     :       (4/7 – 1/2)  

    1/10                      1/1 4 

So Required ratio = X : Y = 1/10 : 1/14 = 7:5

B's 8 days work=(1/12) x 8 = 2/3

Reaining work= 1/3

Now, 1/15 work is done by A in 1 day

Therefore, 1/3 work is done by A in 15 x (1/3) = 5 days