The Taste Test for PTC (Phenylthiourea) Is a Common Class

Short Answer

The taste test for PTC (phenylthiourea) is a common class demonstration in the study of genetics. It is known 70% of the American people are "tasters" and 30% are "non-tasters." Suppose a genetics class of size 20 does the test to see if they match the U.S. percentage of "tasters" and "non-tasters." (Assume the assignment of students to classes constitutes a random process.)
For the random variable x, the number of "non-tasters" in the class,
Find P(3 < x < 9).
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Find the mean of x.
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Find the variance of x.
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