Biostatistics
posted by Louise .
Age(1014)(1519)(2029)(3039) (4044)
Mid 12.5 17.5 25 35 42.5
P(X=x) .003 .100 .500 .300 .097
If we select a birth at random, what is the probability the mother is 19 years or younger?

I'm not sure what you mean by "P(X=x). If it is probability, add the probabilities for the two lower categories to indicate the probability that it is either (1014) or (1519).
Does "Mid" refer to median?
I hope this helps. If not, repost your question in clearer terms.