Which of the following is an example of control?
a. repeating a study 10 times
b. studying the effects of both therapy and no therapy on students
c. performing five different studies of the same drug
d. assigning test subjects to test groups arbitrarily

An initial investment of $100 is now valued at $150. the annual interest rate is 5%, compounded continuously. the equation 100e0.05t = 150 represents the situation, where t is the number of years the money has been invested. about how long has the money been invested? use your calculator and round to the nearest whole number. years

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)

Thanh and her crew are building a stage in the shape of a trapezoid for an upcoming festival. the lengths of the parallel sides of the trapezoid are 14 ft and 24 ft. the height of the trapezoid is 12 ft.what is the area of the stage? enter your answer in the box. ft²