A boy is running at a speed of p km/h to cover a distance of 1 km but due to slippery ground his speed is reduced by q km/h (p > q). If he takes r hours to cover the distance, which of the following condition is true:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \(\displaystyle\frac{1}{r}=(p-q)\)
Time = distance ÷ speed. On the slippery ground his speed falls by \(q\) km/h, from \(p\) to \(p-q\) km/h.
Time for 1 km: \(r=\displaystyle\frac{1}{p-q}\) hours
Taking the reciprocal of both sides: \(\displaystyle\frac{1}{r}=p-q\)