Question

A car is travelling with $5/7$ of its actual speed covers 42 km in 1hr 40 min 48 sec.Find actual speed of the car.

Answer 1

Time taken $=$ $1$ hr $40$ min $48$ sec $=$ $1$ hr $40\frac{4}{5}$ min $=1\frac{51}{75}$ hrs $=\frac{126}{75}$ hrs.

Let the actual speed be $x$ km/hr

$\frac{5}{7}x\times \frac{126}{75}=42$

$x=42\times \frac{75}{126}\times \frac{7}{5}=35$ km/hr.