The mean score was 72%. The standard deviation was 7%. Based on this information, what is the best approximation for the number of students who scored 80% or better?
16
800
309
159

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.

What is the solution to the system of equation graphed belowa.(0,-4)b.(2,5),1),-3)

Simplify this expression. 8x 16(x + y)