Question

A 60-litre tank was full of oil. Sam used 40%of it and poured the rest into a 40 litre tank.

1) What per cent of the 40-litre tank was filled with oil?

2) If Sam used 3 litres of oil daily, what per cent of oil in the 40 litre tank would be used in 10 days?

Answer 1

Capacity of 1stTank =60 litres.
Amount of oil used by Sam=40% of 60 litres.
                                           =(40/100)*60 litres.
                                           =24 litres.
Amount of oil left = (60 - 24) litres
                            = 36 litres.
Acc. to Question, Amount of oil that was left, was poured in 2nd tank with capacity 40 litres.
Now,
Percentage of  oil in 2nd tank=(36/40)*100 %
                                               = 90 %. (1st Part Answer)
Now if 3 litres of oil is being used daily,
Amount of oil used in 10 days = (3*10)=30 litres.
Amount of oil left in the tank = (36-30) = 6 litres.
Now percentage of oil in tank = (6/40)*100 %
                                                     =15%
∴Percentage of oil left in tank = (100 - 15)% = 85% (2nd Part Answer)

Answer 2

1) Tank has amount of oil
= 60 litre
Sam used 40% of it
= 60×40/100
= 24.
Sam used = 60-24
= 36
Sam poured it into 40 litre tank.
The percentage of oil in 40 litre tank
= 36×100/40
= 90%

2) If Sam used 3 litre oil daily means in 10 days
= 3×10
= 30
Water in 40 litre tank = 36 litre
Percentage= 30×100/36 = 250/3
= 83_1/3