Quantitative Aptitude - Arithmetic Ability Questions

Let the present age of person be   x years.

Then, 3(x + 3) - 3(x - 3 ) = x   <=> (3x + 9) - (3x - 9) = x  <=> x = 18..

C.I.= Rs.[4000*(1+10/100)^2-4000]

 =Rs.840

sum=Rs.(420 * 100)/3*8=Rs.1750

capacity of a tank = volume of tank 

= [ (8 x 100) x (6 x 100) x (2.5 x 100) ]/ 1000 litres 

= 120000 litres

Let the C.P of one item is Rs. P
and that of other is Rs. (7500 - P)

According to the data given
C.P = S.P
=> Px(116/100) + (7500-P)x(86/100) = 7500
=> 30P = 105000
=> P = 3500

Required difference between selling prices
= Rs. [(3500/100) x 116] - [(4000/100) x 86]
= 4060-3440
= Rs. 620

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

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.

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