Question

A train travels 8 km in the first quarter of an hour, 6 km in the second quarter and 40 km in the third quarter. find the average speed of the train per hour over the entire journey. (a) 72 km/h (b) 18 km/h (c) 77.33 km/h (d) 78.5 km/h

Answer 1

Answer:

$Option \green {(a)}\: is \: correct$

Step-by-step explanation:

$Distance \: travelled \: in \:the \: first \:quarter\\= 8\:km$

$Distance \: travelled \: in \:the \: second \:quarter\\= 6\:km$

$Distance \: travelled \: in \:the \: third \:quarter\\= 40\:km$

$Total \: time (t) = 3 \: quarters \\= 3\times 15\: minutes \\= 45 \: minutes \\= \frac{45}{60} \:hours$

$Total \:distance \:travelled \\= 8\:km + 6\:km + 40\:km \\= 54 \:km$

$\boxed {\blue {Average \: speed = \frac{Total \: distance \: travelled}{Total \: time\:taken }}}$

$= \frac{54}{\frac{45}{60}}\\=\frac{54\times 60}{45}\\=72 kmhr$

Therefore.,

$Option \green {(a)}\: is \: correct$

•••♪

Answer 2

Answer:

Step-by-step explanation:

72