Quantitative Aptitude - Arithmetic Ability Questions

                                                               Father           Son

5years ago the age of the father & son           5X                X

present the age of the father & son              5X+5             X+5

(present age of father) + (present age of son) = 70

       (5x+5)                 +        (x+5)              = 70

 Then you will get X = 10

Present age of the son (x+5) = 15

From the given data,

let the length, breadth and height of the cuboid are m, n, r

m x n = 12

n x r = 20

r x m = 15

Hence, m x n x n x r x r x m = 12 x 20 x 15

mnr = sqrt of (12x20x15) = 60 cub.cm.

We know that zero can't be in hundreds place. But let's assume that our number could start with zero.

The formula to find sum of all numbers in a permutation is

111 x no of ways numbers can be formed for a number at given position x sum of all given digits

No of 1 s depends on number of digits

So,the answer us

111 x 20 x (0+1+2+3+4+5) = 33300

We got 20 as follows. If we have 0 in units place we can form a number in 4*5 ways. This is for all numbers. So we have substituted 20 in formula.

Now, this is not the final answer because we have included 0 in hundreds place. so we have to remove the sum of all numbers that starts with 0.

This is nothing but the sum of all 2 digits numbers formed by 1 2 3 4 5. Because 0 at first place makes it a 2 digit number.

So the sum for this is 11 x 4 x (1+2+3+4+5).
=660

Hope u understood why we use 4. Each number can be formed in 4x1 ways

So, the final answer is 33300-660 = 32640

P.W = (100 x T.D)/(R x T)  = (100 x 168)/(14 x 2)= 600 

Sum = (P.W + T.D) = Rs. (600+ 168) = Rs.768.