Question with reasonableness test for audit class.

A,B,C,D, and E all have to do with products in the same company.

So I was wondering if I did this right? I don't understand how to analyze or actually calculate the tolerable threshold. Also what am I suppose to compare this number too? Am I suppose to find the total of the tolerable threshold which would be 198? But then I don't understand what to do after. Thank you in advance for the explanation. We did not go over many examples in class.

Actual Sales 2017 1500 2000 A Difference b/w Calculate Expected Sales actual and tolerable 2016 expected threshold 2000 -500 30 1400 600 40 2300 -200 42 2350 50 48 1800 100 38 2100 B D E 2400 1900 *for tolerable threshold, given that 2% of 2017 sales is a reasonable choice Actual Sales 2017 1500 2000 A Difference b/w Calculate Expected Sales actual and tolerable 2016 expected threshold 2000 -500 30 1400 600 40 2300 -200 42 2350 50 48 1800 100 38 2100 B D E 2400 1900 *for tolerable threshold, given that 2% of 2017 sales is a reasonable choice