Given two sets, x = {things that are impossible or untrue} and y = {mathematical statements}, which of the following are in x ∩ y? .
a. cow jumps over the moon.
b. a cat tells you a story.
c. 99 - 2 = 1,000
d. 15^2 = 15
e. candy is sweet.

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Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

If 7x=9y, y/z = 7/5 , then x/z = (a) 2/7 (b) 7/9 (c) 9/5 (d) 9/7 (e) 5/9