Jack swam directly across the pool, diagonally from one corner to another. Which of these is the best estimate of how far he swam?

• A. 75 feet
• B. 95 feet
• C. 65 feet
• D. 85 feet

Answer: (C)

When you go from one corner to the opposite corner of a rectangle, you’re traveling along the diagonal. The distance of that diagonal comes from the Pythagorean theorem: diagonal^2 = length^2 + width^2.

If the pool is about 60 feet long and 25 feet wide, the diagonal is sqrt(60^2 + 25^2) = sqrt(3600 + 625) = sqrt(4225) = 65 feet. So 65 feet is the best estimate for how far Jack swam. The diagonal is longer than either side but not as large as the sum of the sides, and 65 feet matches the standard 25-60-65 right triangle, making it the most reasonable choice among the options.