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Heart weights of mammals Here are some data on the hearts of various mammals:

a. Make an appropriate scatterplot for predicting heart weight from length. Describe what you see.

b. Use transformations to linearize the relationship. Does the relationship between heart weight and length seem to follow an exponential model or a power model? Justify your answer.

c. Perform least-squares regression on the transformed data. Give the equation of your regression line. Define any variables you use.

d. Use your model from part (c) to predict the heart weight of a human who has a left ventricle6.8 cm long.

Short Answer

Expert verified

(a) The scatter plot slope is sloping upwards, hence the direction is positive.

(b) Power model

(c) lny=-0.314+3.139lnx

(d)299.825gms

Step by step solution

01

Part (a) Step 1: Given information

The given data is

02

Part (a) Step 2: Explanation

From the given data the graph is

The reason for the curve is that the points are not on a straight line.

The scatter plot slope is sloping upwards, hence the direction is positive.

The reason for this is that all of the points are fairly close together in the same pattern.

03

Part (b) Step 1: Given information

The given data is

04

Part (b) Step 2: Explanation

The graph is

The model with the most linear pattern in the associated scatter plot is the model for the relationship between the variables." Power Model

05

Part (c) Step 1: Given information

The given data is

06

Part (c) Step 2: Explanation

The logarithm of length is X, and the logarithm of heart weight is Y.

Find the values using the table

a=∑y·∑x2-∑x∑xyn∑x2-∑x2a=-0.314

b=n∑xy-∑x·∑yn∑x2-∑x2b=3.139

then the value of y is

y=a+b.x

y=-0.314+3.139x

The least-square regression equation is

lny=-0.314+3.139lnx.

07

Part (d) Step 1: Given information

The given data is

08

Part (d) Step 2: Explanation

From part (c)

lny=-0.314+3.139lnx

Putting the value of x

lny=-0.314+3.139ln(6.8)

=5.7032

Therefore taking the exponential

y=elnyy=e5.7032

=299.825

The expected heart weight is299.825gms

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