Quantitative Aptitude - Arithmetic Ability Questions

Let the present ages of A and B be 'x' and 'y' respectively

From the given data, 

[(x-2) + (y-2)]/2 = 26

=> x+y = 56

But given the age of A, 5 years hence is 40 yrs => present age of A = 40 - 5 = 35 yrs

=> x = 35 => y = 56 - 35 = 21

=> Age of B = 21 yrs

Given B is 5 years younger to C,

=> Age of C = 21 + 5 = 26 yrs

=> Required Difference between ages of A and C = 35 - 26 = 9 yrs.

16 : 56 :: 32 : ?

Let the required number be 'n'

The given numbers follow a logic that,

16/56 = 2/7

=> 32/n = 2/7

=> 32 x 7/2 = n

=> n = 112.

Hence, 16 : 56 :: 32 : 112.

Let the number be 'N'
Given N + 30N/100 = 390
=> 130N/100 = 390
=> N = 390 x 10/13
=> N = 300.

At the moment the paint is 3 liters of paint and 3 liters of water. We need to add to this to make the new ratio 2 liters paint to 1.5 liters water. As this is equivalent to 4 : 3 we can see that we have the right amount of water, and just need 1 liter of paint to make it correct.

let sum =x . s.i.=x

rate =(100*x)/(x*6)=50/3%

now ,sum =x, s.i= 3x, rate =50/3%

time =(100*3x)/(x*50/3) = 18 years

only (c) is correct since it is divisible by 4.

Let the original number of element  be x then the new no.of elements will be 

            4x5 = K                               

So K must be divisible by 4

Since,      x =  Kx5/4

Given length of iron rod =7 mts and  and diameter of rod = 2 cms 

=> r = 1/100 mts

Therefore,  Volume of one rod = πr2h cu. m =  227×11002×7cu. m = 115000 cu. m

Given volume of iron = 0.88 cu. m 

Therefore, Number of rods = 0.88×500011 = 400.

The mutiplicative inverse of a number is nothing but a reciprocal of a number.

Now, the product of a number and its multiplicative inverse is always equal to 1.

For example :

Let the number be 15

Multiplicative inverse of 15 = 1/15

The product of a number and its multiplicative inverse is = 15 x 1/15 = 1.