Robert is travelling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph, he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?
8 kmph
11 kmph
12 kmph
14 kmph
Explanation:
Let the distance travelled by x km.
Then,$\dfrac{x}{10}-\dfrac{x}{15}$=2
$\Rightarrow$ 3x - 2x = 60
=> x = 60 km.
Time taken to travel 60 km at 10 km/hr =$\left( \dfrac{60}{10} \right)$hrs=6hrs
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
$\therefore$ Required speed =$\left( \dfrac{60}{5} \right)$kmph
=12kmph
Let the distance travelled by x km.
Then,$\dfrac{x}{10}-\dfrac{x}{15}$=2
$\Rightarrow$ 3x - 2x = 60
=> x = 60 km.
Time taken to travel 60 km at 10 km/hr =$\left( \dfrac{60}{10} \right)$hrs=6hrs
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
$\therefore$ Required speed =$\left( \dfrac{60}{5} \right)$kmph
=12kmph