Question

Flying with the wind, a plane flew 1,200 mi in 4 h. Against the wind, the plane required 6 h to fly the same distance. Find the rate of the plane in calm air and the rate of the wind.

Answer 1

Rate of plane = 250 mph

Rate of wind = 50 mph

Explanation:

• Let the speed of the plane in calm air be x mph
• & speed of the wind be y mph
• Speed of plane with wind = (x + y) mph
• Speed of plane against wind = (x - y) mph
• Formula relating speed, time and distance is given as: speed*time = distance
• According to the first condition: (x+y)*4 = 1200
• -> x + y = 300 (1)
• According to the second condition: (x-y)*6= 1200
• -> x - y = 200 (2)
• Adding equations (1) & (2), we find:
• 2x = 500
• -> x = 250 (Dividing 500 by 2)
• -> y = 50 (Plugging x = 250 in eq 1)
• Rate of plane = 250 mph
• Rate of wind = 50 mph