Quantitative Aptitude - Arithmetic Ability Questions

Let the number of boys in the group originally be x.
Total weight of the boys = 30x
After the boy weighing 35 kg joins the group, total weight of boys = 30x + 35
So 30x + 35 + 31(x + 1) = > x = 4.

F = Rs. 2160

TD = Rs. 360

PW = F - TD = 2160 - 360 = Rs. 1800

True Discount is the Simple Interest on the present value for unexpired time

=>Simple Interest on Rs. 1800 for unexpired time = Rs. 360

Banker's Discount is the Simple Interest on the face value of the bill for unexpired time

= Simple Interest on Rs. 2160 for unexpired time

=(360/1800)* 2160

= (1/5) * 2160

=Rs. 432

Let the length of the train e x meter, and let the speed of train be y km/h, then

x=y+3×518×36   --------(1)   and   

x=y+6×518×30  ---------(2)

From eq (1) and (2), we get      

y = 12 km/h

Therefore,  x=(y+3)×518×36   =>  x= 150 m

Let Ben’s age now be B

Anita’s age now is A.

(A - 6) = P(B - 6)

But A is 17 and therefore 11 = P(B - 6)

11/P = B-6

(11/P) + 6 = B

Given ratio of pens and pencils = 3 :2

Number of Pens = 3x

Number of Pencils = 2x

Average number of pencils & Pens = 3x + 2x2 = 180

5x = 360

=> x = 72

Hence, the number of pencils = 2x = 72 x 2 = 144.

Suppose they meet x hrs after 8 a.m

then,

[Distance moved by first in x hrs] + [Distance moved by second in (x-1) hrs] = 330.

Therefore, 60x + 75(x-1) = 330.

 => x=3.

So,they meet at (8+3) i.e, 11a.m.