Question

9. If the speed of a train is increased by 5 km/h from its
normal speed it would have taken 2 h less to cover 300
km. What is its normal speed?​

Answer 1

Solution

let ,the normal speed is =(x )Km/h

now...time to cover 300km distance is...

=(300/X)hours

now.. the new speed is=(X+5)km/HR

time =300/(X+5) hours

now according to the problem...

$= > \frac{300}{x} - \frac{300}{x + 5} = 2 \\ = > 300x + 1500 - 300x = 2x {}^{2} + 10x \\ = > 2x {}^{2} + 10x - 1500 = 0 \\ = > x {}^{2} + 5x - 750 = 0 \\ = > x {}^{2} + 30x - 25x - 750 = 0 \\ = > (x + 30)(x - 25) = 0 \\ \\ therefore \\ x = 25(coz \:speed \: can \: not \: be \: negative \: \: \: \: \: \:$

the normal speed was...25km/hr