Question

Aeroplane covers four distance at different speeds of 100,200,300,00 kms/hr.the average speed is?

Answer 1

We can solve this better by using the direct formula for fetching average speeds.

= 2 (S1 S2) / (S1+S2)

Case 1 taking S1 = 100, S2 = 200

= 2*100*200/(100+200)

= 40000/300

= 400/3

= 2 (S1 S2) / (S1+S2)

Case 2 taking S1 = 300, S2 = 400

= 2*300*400 ( (300+400)

= 240000/700

= 2400/7

Case 3

S1 = 400/3, S2 = 2400/7

= 2 (S1 S2) / (S1+S2)

= (2 * 400/3 * 2400/7) / (400/3+2400/7)

= (1920000/21) / (10000/21)

= 1920000/21 * 21/10000

= 1920000/10000

= 192 km/hr is the required average speed.