Te shelf life (duration until the expiration date in months) of certain ointment is known to have a normal distribution. a sample of size 120 tubes of ointment gives x = 36.1 and s = 3.7.

a. construct a 95% confdence interval of the population mean shelf life.

b. suppose a researcher believed before the experiment that 4 σ = . what would be the required sample size to estimate the population mean to be within 0.5 month with 99% confdence?

Vikram is studying the square pyramid below. on st to find the surface area of the pyramid, in square inches, vikram wrote (33.2) (34 ikram wrote (33.2)(34.2)+43(34.2)(284) what error did vikram make? o he used the same expression for the area of all four lateral faces. he used the wrong expression to represent the area of the base of the pyramid. o he used the wrong value as the height when he found the area of the lateral faces. he used an expression for surface area that only finds the total area of three faces.