Help me with number 4 please

Apple Ine CON SOLDATED STATEMENTS OF OPERATIONS On millions, except number of shares which are refected in thousands and per share ameun) ears ende Net saies 21560 201 2) Based on the above tables, Calculate the following growth rates between 2017 and 2016 Growth % -Lo,370 B.5% 2017 2016 Sales 674 Net A/R Allowance 9.9% 58 5 3 Gross A/R 3 41% 240 2 IS 807 6 Based solely on questions #1 & #2, any concern of Apple's A/R and sales being out of normal relationship? i.e. any manipulation) Yes or no and why 3) me nuncers ore ven simlar 4) What if the industry Apple operates in has an allowance to gross receivables ratio of 2% on average. Is Apple ver/understating revenues and by how much? (201