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In the surface area formula for cylinders which expressionrepresents the lateral area

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?

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.