Question

Radha walks to her office 5 km away from home. In the morning, she covers the distance in 1 hour whereas, while returning home in the evening, she takes 15 more minutes to cover the same distance. Find her average speed (in km/h) during the two-way journey.

• A. 4 2/3
• B. 4 4/9
• C. 3 1/8
• D. 3 3/5

Answer 1

Answer:

B. 4 4/9

Distance one way = 5 km
Total distance = (5 + 5 = 10) km

Time taken:

• Morning = 1 hour

• Evening = (1 \text{ hr } 15 \text{ min} = 1.25) hours

Total time:
Distance one way = 5 km
Total distance = (5 + 5 = 10) km

Time taken:

• Morning = 1 hour

• Evening = (1 \text{ hr } 15 \text{ min} = 1.25) hours

Total time:
$1 + 1.25 = 2.25 \text{ hours}$
Average speed:

$\text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{10}{2.25}$
$= \frac{40}{9} \approx 4.44 \text{ km/h}$

$1 + 1.25 = 2.25 \text{ hours}$

Average speed:

$\text{Average speed} = \frac{\text{Total distance}}{\text{Total time}} = \frac{10}{2.25}$

$= \frac{40}{9} \approx 4.44 \text{ km/h}$

Final Answer:

$\boxed{\frac{40}{9} \text{ km/h} \approx 4.44 \text{ km/h}}$

We already got:
$\text{Average speed} = \frac{40}{9} \text{ km/h}$

Convert to mixed fraction:
$\frac{40}{9} = 4 \frac{4}{9}$