Question

Ram covers a distance of 100 km with a variable speed. For the first half of his journey, the speed was 20km/h and during the rest of his journey the speed was 40km/h. Calculate the average speed of Ram during the whole journey?

Answer 1

Answer:

for first half journey,

t1=50/20=2.5h

for second half journey,

t2=50/40=1.25h

so, AV=100/3.75=26.66km/h

Answer 2

Answer:

Average speed of ram during the whole course of his motion is 26.66 Km/h.

Explanation:

Distance covered = 100 km

Time taken by ram to cover 60 km with speed 20 km/h ( $\sf{t_1}$ ) = $\dfrac{50}{20}$ h

$\longrightarrow$ $\sf{t_1}$ = $\dfrac{5}{2}$ h

Time taken by ram to cover next 50 km ( $\sf{t_2}$ ) = $\dfrac{50}{40}$ h

$\longrightarrow$ $\sf{t_2}$ = $\dfrac{5}{4}$ h

$\therefore$ Total time = $\sf{t_{1} + t_{2}}$

$\longrightarrow$ Total time = $\dfrac{5}{2}$ + $\dfrac{5}{4}$

Taking LCM,

$\longrightarrow$ Total time = $\dfrac{10+5}{4}$

$\longrightarrow$ Total time = $\dfrac{15}{4}$

Now, let's calculate average speed,

Average speed = $\sf{\dfrac{Total\:distance\:travelled}{Total\:time\:taken}}$

$\longrightarrow$ Average speed = $\dfrac{100}{15}$ × 100

$\longrightarrow$ Average speed = 26.66 km/h

Hence, Average speed of ram during the whole course of his motion is 26.66 Km/h.