Question

Tim goes on a car journey.

Answer 1

Answer:

1. Attached

2. 25 mph

Step-by-step explanation:

1. Tim travels first 15 minutes $=\frac{1}{4}$ hour at average speed of 40 mph and passed

$40\times \dfrac{1}{4}=10\ miles$

2. Time stops for 25 minutes (distance traveled = 0 miles).

3. He then completes the journey at an average speed of 45 mph. The total journey time is 1 hour, then he was travelling at 45 mph for

$60-15-25=20\ minutes=\dfrac{1}{3}\ hour$

and covered

$45\times \dfrac{1}{3}=15\ miles.$

The distance-time graph for his journey is attached.

Find the average speed for the whole journey:

$\text{Average speed}=\dfrac{\text{Total distance}}{\text{Total time}}=\dfrac{10+15}{1}=25\ mph$