JAMB - Mathematics (2017 - No. 21)
A man covered a distance of 50 miles on his first trip, on a later trip he traveled 300 miles while going 3 times as fast. His new time compared with the old distance was?
three times as much
the same
twice as much
half as much
설명
Let the speed of the 1st trip be x miles/hr
and the speed of the 2nd trip be 3x miles/hr
Speed = distance/time
∴ Time taken to cover a distance of 50 miles on the 1st trip
= \(\frac{50}{xhr}\)
time taken to cover a distance of 300 miles on the next trip
= \(\frac{300}{3xhr}\)
= \(\frac{100}{xhr}\)
∴the new time compared with the old time is twice as much
and the speed of the 2nd trip be 3x miles/hr
Speed = distance/time
∴ Time taken to cover a distance of 50 miles on the 1st trip
= \(\frac{50}{xhr}\)
time taken to cover a distance of 300 miles on the next trip
= \(\frac{300}{3xhr}\)
= \(\frac{100}{xhr}\)
∴the new time compared with the old time is twice as much