What is the probability that a random five-card hand has (a) exactly one pair (no three of a kind or two pairs)? comment on the answers (a) 13 × c(4, 2) × c(48, 3)/c(52, 5), (b) 13 × c(4, 2) × 48 × 44 × 40/c(52, 5), and (c) (52 × 3 × 48 × 44 × 40)/ (52 × 51 × 50 × 49 × 48).

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.