Question

A plane left 30 min later than its scheduled time to reach its destination 1500 km away. In order to reach in time it increases its speed by 250 km/h. What is its original speed

• A. 1000 km/h
• B. 750 km/h
• C. 600 km/h
• D. 800km/h

Answer 1

Answer: (B)

750 km/h

Answer 2

Let the original times be $T$ hours and original speed be $x$ km/h
$\frac{1500}{x}=T$

$\frac{1500}{x+250}=T-\frac{30}{60}$

Solving equations (i) and (ii), we get
Speed of plane $=x=750$ or $-1000$ (not possible)
$\therefore$ $x=750$ km/h
The correct option is (B)