Using Rstudio. I am having trouble isolating just the five years olds from this data set of multiple ages. Assume that for all the $5$ years old children, over $50$ pounds considered as overweight. Assume $10\%$ of $5$ years old children are overweight. Does the data support this assumption? Find a $95\%$ CI for

the mean of weight of all the $5$ years old children and a $90\%$ CI for

the standard deviation of the weight of the $5$ years old children