1. The problem states that Murphy's score changed from 2 under par to 3 over par. 2. Being "2 under par" means his score was $-2$ relative to par. 3. Being "3 over par" means his score was $+3$ relative to par. 4. To find the change in score, subtract the initial score from the final score: $$\text{Change} = 3 - (-2)$$ 5. Simplify the expression: $$3 - (-2) = 3 + 2 = 5$$ 6. Therefore, Murphy's score increased by 5 strokes relative to par.