A credit note was issued on 31 December for R9 920. Goods were sold with a mark-up of 60%. No entry has been made of this
transaction.

sales is 3 345 000
cost of sales is 2 090 625​

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.