Write the quadratic equation whose roots are 3 and 4, and whose leading coefficient is 2.
(use the letter x to represent the variable.)

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.