Data on the 5000 largest mutual funds shows which funds provided a high 5-year return and a high 10-year return. Of the 5000 mutual funds surveyed, 4000 funds had a high 5-year return, 1800 had a high 10-year return, and 1200 had both a high 5-year return and a high 10-year return.
(a) What is the probability of a mutual fund having a high 5-year return or a high 10-year return?