Question

A man covers three equal distances

at the speed of 30 km/h, 15 km/h and 10

km/h respectively, then find out his

average speed during the whole journey.

A 30.76 km/h

B. 31.76 km/h

C. 32.76 km/h

D. 33.76 km/h​

Answer 1

Answer:

32.76km/h

Step-by-step explanation:

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Answer 2

The average speed of the whole journey is "15 $\dfrac{km}{h}$ ".

Step-by-step explanation:

We know that, if three equal distances are covered at different speeds of A, B and C km/h respectively,

Average speed during whole journey = $\dfrac{3ABC}{AB + BC + CA}$

Here, A = 30 $\dfrac{km}{h}$, B = 15 $\dfrac{km}{h}$ and

C = 10 $\dfrac{km}{h}$,

∴ Average speed during whole journey

= $\dfrac{3(30)(15)(10)}{(30)(15)+ (15)(10)+ (10)(30)}$

= $\dfrac{3(30)(15)(10)}{450+ 150 + 300}$

= $\dfrac{3(30)(15)(10)}{900}$

= 15 $\dfrac{km}{h}$

No option matched.

Hence, the average speed of the whole journey is 15 $\dfrac{km}{h}$ .