A frequency table of grades has five classes​ (A, B,​ C, D,​ F) with frequencies of ​, ​, ​, ​, and respectively. Using​ percentages, what are the relative frequencies of the five​ classes?

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?