You use 4 boxes of rice to serve 13 people. if you want to serve 39 people, what should you do?
a)3 times as many boxes of rice
b)12 more boxes of rice
c)4 times as many boxes of rice
d)26 more boxes of rice

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.