Suppose the heights of the members of a population follow a normal distribution. if the mean height of the population is 68 inches and the standard deviation is 4 inches, 99.7% of the population will have a height
within which of the following ranges?

a. 56 inches to 80 inches
b. 64 inches to 72 inches
c. 60 inches to 76 inches
d. 52 inches to 84 inches

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.