Please help me understand how to solve this geometry problem, if possible please keep it as simple as possible. Thanks for your time :)

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?

Solve: 25 points find the fifth term of an increasing geometric progression if the first term is equal to 7−3 √5 and each term (starting with the second) is equal to the difference of the term following it and the term preceding it.

What is the point of inflection for the function f(x)=2cos4x on the interval (0, pi/2)