Question

Tom drives a truck. His regular trip is a distance of 280 km. He drives at an average speed of 80 km/h.

For safety reasons Tom’s boss puts a speed limiter on his truck. This reduces Tom’s average speed by 10 km/h.

Answer 1

Distance = 280 km

Average speed = 10 km/h

Time = distance/speed

Time = 280 km/ 80 km/h
=3.5 hours

If the driver’s speed reduced by 10 km/h
Speed = 80 - 10 = 70 km/h

Time = distance/ speed

Time = 280 km / 70 km/h
= 4 hours

The time would be longer by : 4 -3.5 = 0.5 hours

0.5 * 60 = 30 minutes

It would be longer by 0.5 hours or 30 minutes

Answer 2

4 hours.

Explanation:

Tom drives his regular trip of distance = 280 km.

He drives at an average speed of = 80 km/hour

To calculate the time the formula is

Time =
`\frac{\text{total distance}}{\text{speed}}`

He takes time to complete his trip =
`(280)/(80)`

= 3.5 hours

His boss puts a speed limiter on his truck. This reduces Tom's average speed by 10 km/hour

Now the new speed would be = 80 - 10 = 70 km/hour.

=
`(280)/(70)`

= 4 hours

Earlier Tom took 3.5 hours now he will take 4 hours to complete his trip.