If r is the radius of a circle and d is its diameter, which of the following is an equivalent formula for the circumference c=2πr?
a. c=2πd
b. c=πd
c. c=πr2
d. c=πdr

The thickness of photoresist applied to wafers in semiconductor manufacturing at a particular location on the wafer is uniformly distributed between 0.2070 and 0.2171 micrometers.(a) determine the proportion of wafers that exceeds 0.2125 micrometers of photoresist thickness. (round your answer to 3 decimal places.)enter your answer in accordance to the item a) of the question statement(b) determine the mean of x. (round your answer to 4 decimal places.)enter your answer in accordance to the item b) of the question statement micrometers(c) determine the variance of x. (round your answer to 8 decimal places.)enter your answer in accordance to the item c) of the question statement micrometers2