Megan has a bag of 6 green, 1 yellow, and 3 purple blocks. She draws a block, replaces it, and then draws another block. What is the probability that the two blocks are the same color?

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?

What multiplys to be 1 but adds up to be 4

How is this equation completed? i cannot find any examples in the book.