Bill has earned 45,000 for the last two years. prior to that, bill earned 42,000 40,000 38,000 what's bills average income in the last 5 years?

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.