Question
A bus was travelling from Jaipur to Udaipur was delayed
by 15 minutes and made up for the delay on a section of 85 km travelling with a speed 12 km per hour higher than its normal speed. Find the approximate original speed of the bus?Solution
Let original speed = 'x' km/hr. Time to cover 85 km at normal speed = 85/x . Time to cover 85 km at increased speed (x+12) = 85/(x+12) Time difference = 15 minutes = 1/4 hours 
Simplify and solve: 
Solve quadratic equation: Using the quadratic formula, x = 58.15  x = 58.15 km/hr.
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