Quantitative Aptitude - Arithmetic Ability Questions

By trial and error method, we get
2880/3 = 960 is not a perfect square
2880/4 = 720 is not a perfect square
2880/5 = 576 which is perfect square of 24
Hence, 5 is the least number by which 2880 must be divided in order to make it into a perfect square.

It is the same as a person with 20 years more age  replaces an existing person of the group ( or village)

Since the total age of the village having n persons, is being increased by 20 years and the average age of village is being increased by 1 year, hence there are total 20 people in the village.

Alternatively :  ( n x 42 ) + 20 = ( n x 43 )

                          => n=20

Let Raju's age at the time of his marriage = X years

Then from given data

=> X + 8 = 6/5 X

X = 40.

Since got married 8 years ago, his present age  = 48

His sister is 10 years younger => 48 - 10 = 38 years.

Part filled by (A + B) in 1 minute = (1/60 + 1/40) = 1/24
Suppose the tank is filled in x minutes.
Then, x/2(1/24 + 1/40) = 1
(x/2) * (1/15) = 1 => x = 30 min.

Total cost of 4 cars =  1+2 = 3 lakh

Total S.P of 4 cars = 3 x 1.5 = 4.5 lakh   (Since S.P = 100 + Gain%100 x C.P)

 S.P of 1 car = 1.2 lakh 

S.P of rest 3 cars = 4.5 - 1.2 = 3.3 lakh

 Average S.P of all the 3 cars = 1.1 lakh

Let the present ages of Mahesh, Nilesh and Ramesh be k, l and m respectively.
k/l = 5/x ------ (1)
k = m - 18 ------ (2)
m + 9 = 47 ------ (3)
k - l = m ----- (4)
(3) => m = 47 - 9 = 38 years
(2) => k = 38 -18 = 20 years
(1) => 20/l = 5/x => l = 4x
(4) => 4x - 20 = 38
=> 4x = 58 => x = 14.5

Here clock-wise and anti-clockwise arrangements are same.

Hence total number of circular–permutations: 18P122*12 = 18!6*24