Question

An express train takes 1 hour less then a passenger train to travel 132 km between Mysore and Bangalore. If the average speed of the express train is 11 km/hr more than that of the passenger train, form the quadratic equation to find the average speed of express train.

Answer 1

Let $v$ be the arg. speed of the passanger train

$\therefore \frac{132}{v}=\frac{132}{v+11}+1$ (given information)

$132v+132\times 11=132v+v^2+11v$

$v^2-11v-132\times 11=0$

$v^2-44v+33v-132\times 11=0$

$v(v-44)+33(v-44)=0$

$(v-44)(v+33)=0$

$\downarrow$ $\downarrow$

$v=44$ $v=-33$ (not allowed)