I'M taking a test and I really need help with these

Acylinder and its dimensions are shown. which equation can be used to find v, the volume of the cylinder in cubic centimeters?

Solve for n? [tex]z = \frac{3}{4} mn[/tex]

Aparticular telephone number is used to receive both voice calls and fax messages. suppose that 25% of the incoming calls involve fax messages, and consider a sample of 25 incoming calls. (a) what is the expected number of calls among the 25 that involve a fax message?