Question

A researcher collects data on the relationship between the amount of daily exercise an individual gets and the percent body fat of the individual. The following scores are recorded. Individual 1 2 3 4 5 Exercise (min) 10 18 26 33 44 % Fat 30 25 18 17 14 Based on the above data, if an individual exercises 20 minutes daily, his predicted % body fat would be _________.

Answer 1

Answer: approximately 24

Explanation:

We need to plot a regression line.

So we fit a model using the regression of Y on X, that an equation that predict Y for a given X using:

(Y -mean(Y ))= a(X-meanX)...........1

Where the formular of a is given the attachment.

N= the of individuals = 5

Y = amount of fat

X = time of exercise

mean(X )= sum of all X /N

= 131/5 = 26.2

mean(Y) = sum of all Y/N

= 104/5 = 20.8

a = N(SXY) - (SX)(SY)/ NS(X²) -(SX)²......2

SXY = Sum of Product X and Y

SX= sum of all X

SY = Sum of all Y

S(X²)= sum of all X²

(SX) = square of sum of X

a = -0.478

Hence we substitute into 1

Y-20.8 = -0.478 (X-26.2)

Y -20.8 = -0.478X - 12.524

Y = -0.478X + 33.324 or

Y = 33.324 - 0.478X (model)

When X = 20

Y = 33.324 - 0.478 × 20

Y = 33.324 - 9.56

Y = 23. 764

Y =24(approximately)

Carefully meaning of formula used in attachment to the solution they are the same.