21. ACT Test One hundred students in your school took the ACT test. Assuming that a normal distribution existed after the results, bow many of the students scored within one standard deviation of the mean? (Give the percent and the number.)

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.