Karolyn is arranging her art project, science project, and math project on her desk. The tree diagram below shows the sample space.
A tree diagram is shown. The first three choices are art, science, and math. From art, one branch is math, science and the other branch is science, math. From science, one branch is art, math and the other branch is math, art. From math, one branch is art, science and the other branch is science, art.
Based on the tree diagram, what is the probability that the science project is first?
one over six
three over six
four over six
two over six