Leonard did this work to solve an equation. did he make an error?

Bed a is seven feet long. bed b is 7/8 of bed a. bed c is 7/8 of bed b. bed d is 7/8 of c. a. come up with an expression for the length of bed d. b. what is the length of bed d?

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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?