The probability of event a is x, and the probability of event b is y. if the two events are independent, which of these conditions must be true?
a. p(b|a) = y
b. p(a|b) = y
c. p(b|a) = x
d. p(a and b) = x + y
e. p(a and b) = x/y
p(a)

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

Sally deposited money into a savings account paying 4% simple interest per year. the first year, she earned $75 in interest. how much interest will she earn during the following year?

△abc is similar to △xyz. also, side ab measures 6 cm, side bc measures 18 cm, and side xy measures 12 cm. what is the measure of side yz ? enter your answer in the box.