新SAT数学OG样题-Multiple choice题型例题（2）

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The mean number of students per classroom, y, at Central High School

can be estimated using the equation y = 0.8636x + 27.227, where x represents

the number of years since 2004 and x 10. Which of the following statements is the best interpretation of the number 0.8636 in the context of this

problem?

新SAT数学OG样题-Multiple choice题型解析汇总，点击查看

A. The estimated mean number of students per classroom in 2004

B. The estimated mean number of students per classroom in 2014

C. The estimated yearly decrease in the mean number of students per

classroom

D. The estimated yearly increase in the mean number of students per

classroom

Content: Heart of Algebra

Key: D

Objective: You must interpret the slope of an equation in relation to the

real-

world situation it models. Also, when the models are created from data,

you

must recognize that these models only estimate the independent variable,

y,

for a given value of x.

Explanation: Choice D is correct. When an equation is written in the

form y = mx + b, the coefficient of the x-term (in this case 0.8636) is the

slope.

The slope of this linear equation gives the amount that the mean number

of

students per classroom (represented by y) changes per year (represented by

x).