A trader bought 55 articles. Some of them cost 250 naira and d rest at 500 naira each The total cost of the article is 7500 naira How many of each type were bought?​

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?