Question

A linear function can be used to model the decrease in rainfall measured since 1880. The decrease in annual rainfall has been a constant 0.12 inches per year. Let x represent the number of years since 1880, when measurements began, and let y represent the annual rainfall. The initial measurement in 1880 was 54.3 inches. Use the linear function to predict the annual rainfall in the 101st year after recordkeeping began. Round to the nearest hundredth.

Answer 1

• 42.18 inches

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In the context of the problem, - 0.12 inches per year represents the slope (negative to show a decrease) of the line and 54.3 inches represent the y-intercept as the starting point.

Considering m = - 0.12 and b = 54.3 in the slope-intercept equation:

• y = mx + b
• y = - 0.12x + 54.3

Find the value of y when x = 101:

• y = - 0.12(101) + 54.3 = 42.18