Question

Meenakshi cycles to her school at an average speed of 12 km/hr and takes 20 minutes to reach her school. If she wants to reach her school in 12 minutes, her average speed should be:

• A. $\frac{20}{3}$ km/hr
• B. 16 km/hr
• C. 20 km/hr
• D. 15 km/hr

Answer 1

The correct option is C 20 km/hr

As speed increases, the time decreases and hence this is a case of inverse variation.

Let x be the required average speed.

Time (in min)	Average speed (in km/hr)
20	12
12	x

Using the arrow method,
$⟹\frac{12}{x}$ = $\frac{12}{20}$

Hence, $x$ = 20

$\therefore$ The average speed should be 20 km/hr.