Describe the process of solving a proportion and explain how you would use this in trigonometry, similar triangles, or any other situation. Must be at least 1 paragraph

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.