What is the formula for circumference of a circle given the diameter? O C= πr
О С = 2πr
O C = πd
O C= 2πd

Anyone know? will mark brainliest if you're correct!

Atextile fiber manufacturer is investigating a new drapery yarn, which the company claims has a mean thread elongation of 12 kilograms with a standard deviation of 0.5 kilograms. the company wishes to test the hypothesis upper h subscript 0 baseline colon mu equals 12 against upper h subscript 1 baseline colon mu less-than 12 using a random sample of n equals 4 specimens. calculate the p-value if the observed statistic is x overbar equals 11.8. round your final answer to five decimal places (e.g. 98.76543).

How do you determine if an ordered pair is a solution to a given equation?