Question

A car covers $300km$ at a constant speed. If its speed was $10kmph$ more, it would have taken $1h$ less to travel the same distance. Find the speed of the car.

• A. $60kmph$
• B. $50kmph$
• C. $40kmph$
• D. $75kmph$

Answer 1

The correct option is B $50kmph$

Let speed of car be x km/h.

and total time in journey be 't'

then

Given $x=\frac{300}{t}$

xt=300-----(1)

and if speed =x+10

time=t-1

x+10=$\frac{300}{(t-1)}$

(x+10)(t-1)=300---(2)

xt-x+10t-10=300

10t-x=310-300=10

10t-x=10

10t-$\frac{300}{t}$=10

$10t^2-10t-300=0$

$t^2-t-30=0$

(t-6)(t+5)=0

t=6 & $t\ne -5$

if t=6 then x=$\frac{300}{6}$=50

speed of car be 50 km/h

and time journey be 6 hrs.