Question

Robert is travelling on his cycle and has calculated to reach point A at 2 pm if he travels at 10 km/h, he will reach there at 12 noon if he travels at 15 km/h. At what speed must he travel to reach A at 1 pm?

Options

• 8 km/h

• 11 km/h

• 12 km/h

• 14 km/h

Answer 1

12 km/h
Explanation:
Let the distance travelled be x km.

Then, `x/10-x/15=2`

⇒ `3x-2x=60`

⇒ `x=60` km

Time taken to travel 60 km at 10 km/h

= `(60/10)h=6h`

So, Robert started 6 h before 2 pm, i.e. at 8 am.

∴ Required speed = `(60/5)`km/h = 12 km/h