A car travels at a uniform speed of 45 km/h for 210 km and then travels for 420 km at a uniform speed of 70 km/h. What is the average speed of the car during the entire journey?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e 59.06 km/h.
Time taken for the first part = 210 ÷ 45 = 4.67 hours (or 14/3 hours)
Time taken for the second part = 420 ÷ 70 = 6 hours
Total distance = 210 + 420 = 630 km
Total time = 4.67 + 6 = 10.67 hours (or 14/3 + 6 = 32/3 hours)
Average speed = Total distance ÷ Total time = 630 ÷ (32/3) = 630 × (3/32) = 1890 ÷ 32
= 59.06 km/h (approx)