Answer: Longest distance she could measure is 70 mm
Step-by-step explanation:
To find the longest distance from one side to other across the center we have to find the diameter of the lampshade.
As it is given that the distance around the lampshade is 219.8 mm which is equal to the circumference of the lampshade.
Circumference of the lampshade is πD, where D is the diameter of the lampshade
where the value of π=3.14
Divide both sides by 3.14 we get
on solving we get