of the height of -6 feet to eat a snack (where 0 is ground level ) After that he climbed to a height of -3 feet . Express the total gain or loss of feet as a integer

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.