Kylie compared attendance rates and grade averages for 10 students using a scatterplot. She fit the data to a line with the equation y = 0.72x + 28.4, where x is the attendance rate as a percent and y is the grade average as a percent.

Question

Find the expected grade of a student with an attendance rate of 80%

Answer 1

To find the expected grade of a student with an attendance rate of 80%, we can substitute \( x = 80 \) into the equation of the line:

\[ y = 0.72x + 28.4 \]

Substituting \( x = 80 \):

\[ y = 0.72(80) + 28.4 \]

Calculating \( 0.72 \times 80 \):

\[ 0.72 \times 80 = 57.6 \]

Now adding 28.4:

\[ y = 57.6 + 28.4 = 86 \]

Therefore, the expected grade of a student with an attendance rate of 80% is 86%.