Dorothy knows songs and rhymes by memory. she can name most colors and numbers, she can even write the letters of her name. assuming she reached these cognitive and language development milestones at the average age, about how old is dorothy?

Dorothy is "four years old".

A developmental milestone is a capacity that is accomplished by most kids by a specific age and which can include physical, social, enthusiastic, intellectual, and relational abilities, for example, strolling, imparting to others, communicating feelings, perceiving commonplace sounds, and talking. Most four-year-olds can Rhyme, Name and distinguish numerous colors, Draw different shapes, they can count to five, Tell where they live and also Draw pictures that they frequently name and portray.