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Sarah鈥檚 parents are concerned that she seems short for her age. Their doctor has the following record of Sarah鈥檚 height:

(a) Make a scatterplot of these data.

(b) Using your calculator, find the equation of the least squares regression line of height on age.

(c) Use your regression line to predict Sarah鈥檚 height at age 40 years (480 months). Convert your prediction to inches

(2.54cm=1inch).

(d) The prediction is impossibly large. Explain why this happened.

Short Answer

Expert verified

Part (b) The least-squares regression line is Height=71.95+0.0383Age

Part (c) S鈥檚 height will be 100.7677 inches.

Part (d) Predicting Sarah鈥檚 height at age 40 years (480 months) is an extrapolation of the relationship beyond what the data show.

Part (a)

Step by step solution

01

Part (a) Step 1: Given information

Age364851545760
Month869091939495
02

Part (a) Step 2: Concept

A regression line shows how an explanatory variable x affects a response variable y You can use a regression line to forecast the value of y for any value of x by plugging this x into the equation of the line.

03

Part (a) Step 3: Explanation

The scatter plot for the given data is as follows

We can see from the scatter plot that all points have a linear rising trend. As a result, we can conclude that there is a positive relationship between age and height. To put it another way, Age and Height are positively connected.

As a result, a scatterplot is created.

04

Part (b) Step 1: Calculation

The explanatory variable is "age," while the response variable is "height." The output of the least-square regression line using MINITAB is as follows.

Analysis of Regression: Age versus Height

From the above output, the least-square regression line is given by

Height=71.95+0.0383Age

Hence, the least-square regression line is Height=71.95+0.0383Age

05

Part (c) Step 1: Calculation

Part (b) yields the following regression line between Age and Height:

Height=71.95+0.0383Age

We can anticipate Sarah's height at 40years old using the regression line shown above (480months) That means, Sarah's height at 40years (480months) is expected to be, Y=71.95+0.383480

=255.94984cm=255.949842.54inches(\1inch=2.54cm)

=100.7677inches=255.94984cm=100.7677inches

06

Part (d) Step 1: Explanation

The age of 40 years (480 months) is well outside the range of our data's X- values. At such extreme levels, we can't say whether the relationship remains linear. Predicting Sarah's height at 40 years old (480 months) is an extension of the connection beyond the data. As a result, we can conclude that the estimated height is inaccurate.

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