what is the probability of flipping 3 coins on the same side that is getting either all heads or all tails? write the exact decimal answer withput rounding

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?