Question

Sales of a popular toy were about 20 million in 2000 and growing about 5% each year. At this growth rate, the function f(x) = 20(1.05)^x gives the annual number of toys sold in million in the xth year after 2000. Using this model, in about what year will the annual sales surpass 37 million?

Answer 1

Answer: 2013

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Work Shown:

Plug in f(x) = 37. Solve for x. Use logarithms.

f(x) = 20(1.05)^x

37 = 20(1.05)^x

20(1.05)^x = 37

1.05^x = 37/20

1.05^x = 1.85

log( 1.05^x ) = log( 1.85 )

x*log( 1.05 ) = log( 1.85 )

x = log( 1.85 )/log( 1.05 )

x = 12.6088044498867

Round up to the nearest whole number to get x = 13.

In the year 2013, sales exceed 37 million.