Economics—Telecommunications: Many historians have called the period from 1995 to 2010 the...

Economics—Telecommunications: Many historians have called the period from 1995 to 2010 the Communications Age because of the proliferation of handheld phones throughout the world. “We live in the communication age, although some people mistakenly call it the Information Age,” said Andrew Kantor of CyberSpeak. (Source: USA Today.) The number of mobile cellular subscribers globally can be modeled by

where x represents the number of years since 1990, and f(x) represents the number of mobile cellular subscribers internationally, measured in millions. (Source: International Telecommunication Union.)

(a) Evaluate f(10) and interpret.

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(b) Determine and . Are these values in the reasonable domain of f?

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(c) Determine . Is this value in the “reasonable range” of f?