Marvin was completing the square, and his work is shown below. identify the line where he made his mistake. f(x) = 2x2 − 8x + 5. line 1: f(x) = 2(x^2 − 8x) + 5 line 2: f(x) = 2(x^2 − 8x + 16) + 5 − 32 line 3: f(x) = 2(x − 4)^2 − 27

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.