Word problem, lower/upper bounds (maths)

Question

Steve travelled from Ashton to Barnfield

 

He travelled 235 miles, correct to the nearest 5 miles. 

The journey took him 200 minutes, correct to the nearest 5 minutes.

 

calculate the lower bounds for the average speed of the journey.

Give your answer in miles per hour, correct to 3 significant figures."

 

 Could I receive help with this question please.

 

Thank you in advance.

Answer 1

235 miles correct to the nearest 5 miles means anywhere between 232.5<=d<237.5

200 minutes to the nearest 5 minutes means from 197.5 <=t< 202.5

 

speed will be in miles per minutes. the upper bound is when the numerator is high and the denominator is low, that is

237.5/197.5=1.2025 miles per minute.

The lower bound would be the slowest speed divided by the most time, 232.5/202.5=1.148 miles per minute.

 

Hope this helped.