Alexander uses cupric chloride to etch circuit boards. He recorded the room temperature, in C. and the etching
im
rate, in of the cupric chloride.
min
After plotting his results, Alexander noticed that the relationship between the two variables was fairly linear, so
he used the data to calculate the following least squares regression equation for predicting the etching rate from
the room temperature:
1
y = 2 +
What is the residual if the room temperature was 25 C and the cupric chloride had an etching rate of 5
im
min
?

First, think of what you know. you know that the number t the end of the equation will need to be subtracted because it is the money he lost from buying the lawn mower. and your first two weeks have negative profit, so that tells you that c and d are wrong. now you can plug any of the weeks into a and b to see which one works. i'll start with plugging week 1 into a.this isn't right because it says your answer for week one should be -90.so now we need to try the same thing with b.this one got you the right answer, (sometimes if you only check with one of the weeks multiple will work so you need to check with more of the weeks, but it worked out fine here)this means that b is the correct answer.let me know if you need more clarification. i hope this : )