Question

A boy runs for 20 mins at uniform speed of 18kmph. At what speed should he run for the next 40 mins so that the average speed comes 24 kmph ?​

Answer 1

Answer:

Hence the speed of the boy is 27ᴋᴍ/ʜ

ꜱᴛᴇᴩ ʙy ꜱᴛᴇᴩ ᴇxᴩʟᴀɴᴀᴛɪᴏɴ

°Time(t1) = 20minutes

=>Time(t1) =20/60 hours = 1/3 hours

Speed(S1)= 18km/hr

Hence, distance= 18×(1/3) = 6km

° Time(t2)= 40minutes.

=>Time(t2) = 40/60hours = 2/3hours

let the speed be X km per hour.

So, distance= 2x/3 km

Final speed(S2) = 24km/hr

Now, According to the question =>

Final speed = Total distance/total time

=>Final speed = {(6 + 2x)/3}/(2/3+1/3)

=>24 = 6+ (2x/3)

=> 2x = 54

=>x = 27km/h.