An aeroplane covers a certain distance of 670 Kmph in 6 hours. to cover the same distance in 6 1/4 hours, it Must travel at a speed of
Choose the correct choice from the following options
A) 440
B) 540
C) 643
D) 740
E) 250

Rationale: "speed of aeroplane = 670 kmph distance travelled in 6 hours = 670 * 6 = 4020 km speed of aeroplane to acver 4020 km in 25 / 4 = 4020 * 4 / 25 = 643 km answer c ."
Answer: C