Question

On a DVD, information is stored on bumps that spiral around the disk. There are 73,000 ridges (with bumps) and 73,000 valleys (without bumps) across the diameter of the DVD. What is the diameter of the DVD in centimeters? Round your answer to the nearest whole number.

Answer 1

I pretty sure it's 8cm.

Explanation:

I multiplied 73,000 by 0.000074, which resulted in 5.402.
Then, I multiplied 73,000 by 0.000032, which resulted in 2.336.
I added the products together, which gave a sum of 7.738.
Then I rounded to the nearest whole number, which is 8, because the tenth in the decimal (.7) rounds up because it is >4.