Question

David's average driving speed for 5 hours journey was 55 km/h. During his first two hours of journey he drove at 60 km/h, and last two hours he drove at 50 km/h. What was his speed for the fifth hour of the
journey?​

Answer 1

Answer:

TOTAL TIME=5 HOURS

AVERAGE SPEED=55 KM/HR

SPEED IN FIRST 2 HOURS = 60 KM/HR

SUM OF SPEEDS OF FIRST 2 HOURS=60+60

=120 KM/HR

SPEED IN LAST 2 HOURS=50 KM/HR

SUM OF SPEEDS OF LAST 2 HOURS=50+50

=100 KM/HR

LET THE SPEED OF LAST HOUR=X KM/HR

____________________________________

AVERAGE SPEED = SUM OF SPEEDS / NO. OF HOURS

55 KM/HR=(120+100+X) / 5

55=(220+X) / 5

55×5=220+X

275=220+X

275-220=X

55=X

ANS.SPEED OF FIFTH HOUR=55 KM/HR

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I HOPE THIS WILL HELP YOU :))