Question

A train is moving at a speed of 100km/hr. It takes 18mins to reach a station. What should be it's speed if the train wants to reach the station in 15 minutes?​

Answer 1

Answer

120 km / hr

solution

given :

speed = 100km/hr

time = 18mins. = 18/60 hr

we know

speed = distance / time

distance = 100 x 18/60 = 10 x 3km = 30km

now we have distance = 30km

in second case, time = 15mins = 15/60 hr

again

speed = distance / time

30

1

4

= 30 x 4

= 120 km/hr

therefore , the speed of train should be

120km/ hr to reach station in 15 mins.

hope this will help uh

Answer 2

$\huge \bold \color{green}{ \underline{ \underline \red{answer}}}$

$\bold{ \underline{ \underline{given}}}$

case 1st

• speed = 100km/hr

$\bold{ = 100 \times \frac{5}{18} \frac{m}{s} }$

so v = 500/18 m/s

• time taken = 18 mins = 18×60sec

=> t = 18×60sec

• distance,s = ??

we know that..

$distance = speed \times time$

$s = \frac{500}{18} \times 18 \times 60 \\ s = 500 \times 60 \\ s = 30000m$

case 2nd

• time taken = 15min

=> t = 15×60sec

• distance = 30000m
• speed = ??

we know that..

$speed = \frac{distance}{time} \\ \\ v = \frac{30000}{15 \times 60} \\ \\ v = \frac{500 \times 60}{15 \times 60} \\ \\ v = \frac{100}{3} m {s}^{ - 1}$

$so \: v = \frac{100}{3} \times \frac{18}{5} km {h}^{ - 1} \\ v = 20 \times 6km {h}^{ - 1} \\ \implies \: v = 120km {h}^{ - 1}$

so speed of the train in 2nd case is 120km/hr