Question

A car takes $1hour$ less to cover a distance of $200km$ if its speed is increased by $10km/hr$, than its usual speed. What is the usual speed of the car.

Answer 1

Let the usual speed is 'x'km/hr

Distance $\Rightarrow 200km$

$\therefore$ Acc to Ques :-

$\Rightarrow \frac{200}{x}-\frac{200}{x+10}=1$

$200\left[\frac{(x+10)-\left(x\right)}{x(x+10)}\right]=1$

$\frac{200\times 10}{x(x+10)}=1$

$x(x+10)=2000$

$x^2+10x-2000=0$

$x^2+50x-40x-2000=0$

$(x+50)(x-40)=0$

$\therefore x=40km/hr$

$\therefore$ The usuel speed $\Rightarrow 40km/hr$