# A machinist is required to manufacture a circular metal disk with area $2000 cm^2$.

A machinist is required to manufacture a circular metal disk with area 2000 cm^2.

(a) What radius produces such a disk? (Round your answer to four decimal places.)

Answer; 25.23132522 <----- This answer is correct

(b) If the machinist is allowed an error tolerance of ±10 cm2 in the area of the disk, how close to the ideal radius in part (a) must the machinist control the radius? (Round your answers to four decimal places.)

Answer; 25.16816786 cm < r < 25.29432488 cm

What value of ε is given?

Answer;10 cm^2 <----- This answer is correct

What is the corresponding value of δ? (Round your answer to four decimal places.)

0.0632 cm <----- This answer is incorrect

I am confused about how 0.0632 is incorrect I did 25.23132522 − 25.16816786 and rounded the answer. I look at sample problems and the way I solved it is the way it was solved.

• Please use the link to format: math.meta.stackexchange.com/questions/5020/… – scoopfaze Jul 10 at 19:17
• I suspect it's because you rounded up. A $\delta$ value at the extreme you give would actually produce a disk outside the tolerance. You have to round conservatively. – saulspatz Jul 10 at 19:22
• Thank you so very much @saulspatz I ended up getting the correct answer! – JaRhonda Roberts Jul 10 at 19:35