What is the main purpose of the immune system?

a) move blood through the body

b) get rid of waste from the body

c) protect the body from pathogens

d) support the body through bones and muscles

An automated water dispenser fills packets with one liter of water on average, with a standard deviation of 5 milliliter. the manual says that after a year of operation the dispenser should be tested to see if it needs recalibration. a year later a number of filled packets are set aside and measured separately. it is found that the average packet now contains about 0.995 liters. does the dispenser need calibration? explain your answer.

An air conditioning system can circulate 350 cubic feet of air per minute. how many cubic yards of air can it circulate per minute?

The radius of a sphere is 3 inches. which represents the volume of the sphere?