N18 | Maths Made Easy

N18

QUESTION: Mateo drives at an average speed of 45.28 miles per hour for 2.69 hours. Estimate the distance he covered over the course of this journey, and state whether your answer is an overestimate or an underestimate.

 

ANSWER: Firstly, recall that “distance = speed \times time”. Therefore, rounding both values to 1 significant figure, we get the estimated distance covered to be

50 \times 3 = 150\text{ miles}

In this case, both the estimated values are bigger than the actual values. So, since we are multiplying together two bigger values, our result will be bigger. Therefore, this is an overestimate of the distance covered by Mateo during this journey.