A rainfall record contains 50 years of measurements at 5-minute intervals. the annualmaximum rainfall amounts for intervals of 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min are ranked as follows rank Δt in minutes 5 10 15 20 25 30 1 26.2 45.8 60.5 72.4 81.8 89.7 2 25.3 44.0 58.1 69.6 78.6 86.3 3 24.2 42.2 55.8 66.8 75.5 82.8 where the rainfall amounts are in millimeters. calculate rainfall intensity for a 40-year 20-min storm. (use weibull method.)