A computer supply store sells a wide variety of generic replacement ink cartridges for printers. A consumer group is concerned that the cartridges may not contain the specified amount of ink (30 ml)....

A computer supply store sells a wide variety of generic replacement ink cartridges for printers. A consumer group is concerned that the cartridges may not contain the specified amount of ink (30 ml). A random sample of 17 black replacement cartridges was obtained, and the amount of ink (in ml) in each is given in the table below.

Assume the underlying distribution of ink amount is normal.

a. Find a 95% confidence interval for the true mean amount of ink in each black cartridge.

 b. Is there any evidence to suggest the cartridges are underfilled? Justify your answer.