Question

Supriya runs a marathon race in$50$ minutes at an average speed of $48km/hr$ in order to set a national record she need to win the race in $40$ minutes considering that her speed remain constant at what minimum speed she run to set the record

Answer 1

Step 1. Given data

1. Supriya run the marathon race with the average speed to $48km/hr$
2. Supriya complete the race in $50$ minutes
3. To create record Supriya need to complete race in $40$ minutes

Step 2. Formula used

Speed$=\frac{\mathrm{Distance}}{\mathrm{Time}}$

Step 3. Find the average speed required to create record

Supriya run the marathon race with the average speed to $48km/hr$

Supriya complete the race in $50$ minutes

Average speed$=v=48km/hr$

Time$=t=50$ minutes

Distance$=s$

Speed$=\frac{\mathrm{Distance}}{\mathrm{Time}}$

$$\begin{gathered} \Rightarrow s=vt \\ =\frac{48}{60}\times 50\left[\because 1hr=60min\right] \\ =40km \end{gathered}$$

The average speed to cover $40km$ in $40$ minutes is

Speed$=\frac{\mathrm{Distance}}{\mathrm{Time}}$

$$\begin{gathered} =\frac{40}{40}\times 60\left[\because 1hr=60min\right] \\ =60km/h \end{gathered}$$

Hence the required speed is $60km/h$