Question

An airliner concorde flies $2000$ km at a speed of $1600$ km/h and then returns due to bad weather at a speed of $1000$ km/h. Find the average speed for the whole trip.

• A. $1240$ km/hr
• B. $1230.77$ km/hr
• C. $1330$ km/hr
• D. $1245.77$ km/hr

Answer 1

Answer: (B)

$1230.77$ km/hr

While travelling to the destination,

Distance traveled, $d=2000$ km

Speed of the plane $s=1600$ km/hr

Time taken, $t=\frac{d}{s}$

$t_1=\frac{2000}{1600}=1.25$ hours

While returning from the destination,

Distance traveled, $d=2000$ km

Speed of the plane $s=1000$ km/hr

Time taken, $t=\frac{d}{s}$

$t_2=\frac{2000}{1000}=2$ hours

Average speed $=\frac{totaldistancetraveled}{totaltimetaken}$

$=\frac{2000+2000}{1.25+2}$

$=\frac{4000}{3.25}=1230.77$ km/hr