Olivia's garden is only 10 yd and the watermelon plants she wants to grow are 2.5 yd each. how many watermelon plants can she grow

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.