JIPMAT 2024 (QA) - A person travels three equal distances at a speed of 'a' km / hr, 'b' km / hr and ' c ' km / hr respectively. What is the average speed for the whole journey? | PYQs + Solutions

JIPMAT 2024

Arithmetic

Time, Speed & Distance

Medium

A person travels three equal distances at a speed of 'a' $\mathrm{km} / \mathrm{hr}$ , 'b' $\mathrm{km} / \mathrm{hr}$ and ' $c$ ' $\mathrm{km} / \mathrm{hr}$ respectively. What is the average speed for the whole journey?

\frac{a b c}{3(a b+b c+a c)}

\frac{a b c}{a b+b c+a c}

\frac{a b+b c+a c}{abc}

\frac{3 a b c}{a b+b c+a c}

Correct Option: 4

1) For equal distances at different speeds:

Average speed =

\frac{\text{Total Distance}}{\text{Total Time}}

2) If each section is

d

distance:

\newline

Total distance =

3d

Total time =

\frac{d}{a} + \frac{d}{b} + \frac{d}{c}

3) Average Speed =

\frac{3d}{\frac{d}{a} + \frac{d}{b} + \frac{d}{c}}

\frac{3d}{\frac{d(bc + ac + ab)}{abc}}

\frac{3abc}{(ab + bc + ac)}