90 is the answer for you're question
Here’s your answer. I’m just writing for no reason coz this needs to be 20 characters long!
Area of a semi-circle = 1/2 x x r square.
area of larger semi circle
= 1/2 x x 10 square
= 50
area of smaller semi circle
= 1/2 x x 5 square
= 12.5
Total area = 50 + 12.5 = 196 cm square ( to 3 sf ) or 62.5
Answer:
lower bound = 90 - 10 = 80 cm
upper bound = 90 + 10 = 100 cm
lower bound d = 1500 x 80 cm = 120,000 cm
upper bound d = 1500 x 100 cm = 150,000 cm