Question

If you walk at a speed of 20 km/hr from your house, you will reach your school at 9.05 a.m. If you walk at 30 km/hr, then you will reach by 8.55 a.m. Find the distance between your house and school.

• A. 10 km
• B. 50 km
• C. 20 km
• D. 5 km

Answer 1

The correct option is A

10 km

Here, it's clear that the distance you are covering is constant (from your house to school)

$\Rightarrow$ As the speed increases, the time taken will be reduced (inverse relation)

Here, the time difference is 10 min $\Rightarrow$ T1 - T2 = 10 min

Let the distance between house and school be D.

And, time = $\frac{Distance}{Speed}$ $\Rightarrow$ $\frac{D}{20km/hr}-\frac{D}{30km/hr}=\frac{D}{60}hr$

On solving this equation by cross multiplying $\Rightarrow$ $\frac{D}{60}=\frac{10}{60}$

$\Rightarrow$ D = 10 km.