2025年8月国际A卷 · 第 12 题

2025年8月国际A卷 · 原库模块 2 · Q12 原库参考解析

The scatterplot shows data set A, which consists of the weights y, in pounds, of a Labrador retriever puppy at various ages, x, in months. The equation of a line of best fit for the relationship in data set A can be written as \( y=-5.1+8.7x \) , where \( 2\le x\le6 \).

The puppy was weighed again at 9 months old and weighed 52 pounds. Data set B consists of all the data points in data set A as well as the data point (9, 52). The equation of a line of best fit for data set B can be written as \( y=r+sx \), where r and s are constants and \( 2\le x\le9 \). Assuming the equations of the lines of best fit are calculated in the same way, which of the following is the best estimate for the value of s?