A college has raised 75% of the amount it needs for a new building

Ques - A college has raised 75% of the amount it needs for a new building by receiving an average donation of Rs. 600 from the people already solicited. The people already solicited represent 60% of the people, the college will ask for donations. If the college is to raise exactly the amount needed for the new building, what should be the average donation from the remaining people be solicited?

A) 250

B) 300

C) 400

D) 600

Solution - 

Let,

The number of people who has been asked for the donations = 100x

People already solicited = 60% of 100x 

= 60x

Remaining people = 40% of 100x

= 40x

Amount collected from the people solicited = 600 × 60x

= 36000x

Thus,

75% of the amount collected = 36000x

1% = 36000x/75

1% = 480x

Remaining amount = 25%

25% = 25*480x

25% = 12000x

Therefore,

Average donation from remaining people = 12000x/40x

= 300

Hence,

The correct option is (b) 300.