Quantitative Aptitude - Arithmetic Ability Questions

Krish’s age = 3A and Vaibhav’s age = 5A

(3A+9)/(5A+9) = 3/4

=> 4 (3A + 9) = 3 (5A + 9)

=> A = 3

Therefore, Vaibhav’s age = 15 years.

Man walked 6 km at 1.5 kmph, again he walked 8 km at speed of 2 kmph and 40 km at a speed of 8kmph
time taken indivisually:
=> 6/1.5 = 4 m
=> 8/2 = 4 m
=> 40/8 = 5 m

Average speed of man= total distance/ total time
=> 54/13 = 4213 kmph

Let the required no of hectares be x. Then 

More men, More hectares      (Direct proportion)

More days, More hectares      (Direct proportion)

 Men8 : 36Days24:30⋮⋮ 80 :x

=> ( 8 * 24 * x) = (36 * 30 * 80)

=>  x= 450

5% is the rate of interest. 20% of the interest amount is paid as tax.

i.e  80% of the interest amount stays back.

 if we compute the rate of interest as 80% of 5% = 4% p.a., we will get the same value.

The interest accrued for 3 years in compound interest = 3 x simple interest on principal + 3 x interest on simple interest + 1 x interest on interest on interest.

= 3 x (200) + 3 x (8) + 1 x 0.32 =600 + 24 + 0.32 = 624.32

The amount at the end of 3 years = 5000 + 624.32 = 5624.32

 Let the ratio be k : 1. Then,

k * 16.4 + 1 * 15.4 = (k + 1) * 15.8

<=> (16.4 - 15.8) k = (15.8 - 15.4)  <=> k =  0.4/0.6 = 2/3.

Required ratio  = 2/3 : 1 = 2 : 3.

Let the number of workers be x.

Now, Using work equivalence method,

X + (X-1) + (X-2)+ . . . . + 1 = X *55% of X

=> [X * (X+1)] / 2 = X * (55X/100)    [because, Series is in AP. Sum of AP = {No. of terms (first term+ last term)/2} ]

Therefore, X = 10 

Let the number of boys and girls be 8x and 5x.
Total number of students = 13x = 13 * 32 = 416.