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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?

Need this asap if anyone can i would be very grateful. if you could show workings that would really

What adds to be the bottom number but also multiplies to be the top number with 8 on the bottom and 15 on top