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?

Answer: Option A

Let the number of people be x who has been asked for the donations
People already solicited = 60% of x = 0.6x
Remaining people = 40% of x = 0.4x
Amount collected from the people solicited,
= 600 × 0.6x = 360x
360x = 75% of the amount collected
Remaining amount = 25% = 120x
Thus,
Average donations from remaining people,
$$\begin{array}{rl}& =\frac{120\text{x}}{0.4\text{x}}\\ & =300\end{array}$$