Question

A car travels at a constant speed.

It travels a distance of 142.2m, correct to 1 decimal place.
This takes 7 seconds, correct to nearest second.
Calculate the upper bound for the speed of a car.​

Answer 1

see below

Explanation:

Given

• Distance is 142.2 m, correct to 1 decimal place
• Time is 7 seconds, correct to nearest second

To find:

• Upper bound for the speed

Solution

Upper bound for the speed = upper bound for distance/lower bound for time

• Upper bound for distance = 142.25 m (added 0.1/5 = 0.05)
• Lower bound for time = 6.5 seconds (subtracted 1/2 = 0.5)

Then, the speed is:

• 142.25/6.5 = 21.88 m/s
• 21.88 = 21.9 m/s correct to 1 decimal place
• 21.88 = 22 m/s correct to nearest m/s