two nice problems

montex · Joined: 18 Jun 2005 Posts: 23 Location: New Delhi

some boys and some girls, if each child sits on each chair, one boy will have no chair to sit. if 2 boys sit on one chair and one girl occupies one chair, then 3 chirs are unoccupied. How many boys are there?
a) 5
b) 2
c) 7
d) 8

The fuel in a petrol tank is 1/8th of the total cpacity of the tank. if x liters of petrol is filled, the volume of petrol is increased to 1/6th of the tank. If the tank can hold another 40 L of petrols then what is the value of X.
a) 2
b) 7
c) 4
d) 6

tpsthegreat · Joined: 30 Jun 2005 Posts: 19 Location: ahmedabad

(1) for the 1st question.
let number of boy=x,girls=y and chairs =n.
from first case,
x+y=n+1 --------(1)
from 2nd case,
x/2 + y= n-3------(2)

subtract (1) and (2) we get
x=8 is the answer

(2)for 2nd question,

let total capacity be y.
from condition in question (5/6)*y = 40 so y=48Litres
now (1/ Cool

*48 = 6 and (1/6)*48 = 8

so x=8-6=2 litres