Question

MATH 100 POINTS

A train travelled along a track in 120 minutes, correct to the nearest 5 minutes. Jake finds out that the track is 290 km long. He assumes that the track has been measured correct to the nearest 10 km. (a) Could the average speed of the train have been greater than 145km/h?

Answer 1

Its equal to 145km/h

Explanation:

120minutes= 2 hours

290km/2 hours

145km/h

Answer 2

As we are supposed to check if the speed of the train could have been greater than 145 km/h or not so,

(we are checking for the upper bound of speed so distance should be upper bound value and time taken lower bound value, for max speed)

Speed = distance/time taken

Given following:

• distance = 290 km (correct to nearest 10 km) so upper bound: 290 + 5 = 295 km
• time taken = 120 minutes (correct to nearest 5 minutes) so lower bound: 120 - 2.5 = 117.5 minutes = (47/24) h

Now max speed = 300/(47/24) = 7200/47= 153.2 km/h

Yes, the average speed of the train could be greater than 145 km/h.

Greatest average speed = 153.2 km/h.