Problem $4$

The following data are for calculator sales in units at an electronics store over the past nine weeks:

Obtain the trend projection with regression forecast for weeks $10-13.($Enter your responses rounded to two decimal places.$)$

Obtain the error measures. $($Enter your responses rounded to two decimal places.$)$

Find the coefficient of determination $(r^2).$

The coefficient of determination $r^2=$

$.($Enter your response rounded to two decimal places.$)$