If you are going to divide the segment into two pieces with a ratio of 1:3, then one of the pieces must be 1/4 the length of the total segment because 1/4 and 3/4 are in the ratio 1:3 and 1/4 + 3/4 = 1 whole.
Find the midpoint of the segment, and then find the midpoint of the first half.
Use the midpoint formulas:
John
My calculator said it, I believe it, that settles it