Pls help I’m almost done and I’ll give the branliest thing if that’s what it’s called

Which of the following is the true for f(x) = 5cos

Can someone me out here and the tell me the greatest common factor

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.