Can you guys help me find the values of z and y?

Julia chooses a card at random from her set of cards. what is the probability that the card is labeled cat or hamster?

What are the soultion(s) to the quadratic equation 40- x^2=0

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.