A machine makes catheters for use in heart tests The machine

A machine makes catheters for use in heart tests. The machine is adjusted to make catheters of diameter 2 mm. Production records show that when the machine is so adjusted, it will make catheters with population mean diameter 2 mm and with population standard deviation .05 mm. During production, an inspector checks the diameters of catheters to see if the machine has slipped out of adjustment. A random sample of 50 catheters is taken. If the mean diameter for this sample is 2.05 mm, does this indicate that the machine has slipped out of adjustment and the average diameter of the catheters is no longer mu = 2 mm? The best test to use in this situation is a

z-test.

t-test.

2-sample t-test.

1-proportion z-test.

Solution

It compares the sample mean and population mean and sample size is larger than 30. So we use z-test.

Answer: z-test.