A swimming pool 40 feet long and 24 feet wide is surrounded by a concrete sidewalk of uniform width x. The total area enclosed by the pool and sidewalk is 1380 square feet how long is the sidewalk along the length of the pool?

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.