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Solve the system of equations. y= 2x y= x^2 - 15

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?

F(n + 1) = f(n) – 8. if f(1) = 100, what is f(6)?