Question

Starting at home, Ishaan traveled uphill to the gift store for 18 minutes at just 10 mph. He then traveled back home along the same path downhill at a speed of 30 mph. What is his average speed?

Answer 1

Average speed = (Speed 1 + Speed 2)/ 2

= (10 + 30)/ 2

= 20 mph

Answer 2

Given :

Starting at home, Ishaan traveled uphill to the gift store for 18 minutes at just 10 mph.

He then traveled back home along the same path downhill at a speed of 30 mph.

To Find :

What is his average speed?

Solution:

Speed on going = 10 mph

Time on going gift store = $18 minutes = \frac{18}{60}$

Distance = $Speed \times Time$

Distance = $10 \times \frac{18}{60}=3 miles$

Speed on downhill = 30 mph

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

Time = $\frac{3}{30}$

Average speed = $\frac{\text{Total distance}}{\text{Total time}}$

Average speed = $\frac{3+3}{\frac{18}{60} +\frac{3}{30}}=\frac{6}{\frac{18+6}{60}} = 15 mph$

Hence His average speed is 15 mph