The annual rainfall values at a station P for a period of 20 years are as follows: Annual Rainfall Annual Rainfall (cm) (cm) 120.0 101.0 84.0 109.0 68.0 106.0 92.0 115.0 102.0 92.0 95.0 88.0 76.0 84.0 Year 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 Year 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 95.0 90.0 70.0 89.0 80.0 90.0 Determine (a) The value of annual rainfall at P with a recurrence interval of 15 years. (b) The probability of occurrence of an annual rainfall of magnitude 100 cm at station P. (c) 75% dependable annual rainfall at the station. [Hint: If an event (rainfall magnitude in the present case) occurs more than once, the rank m = number of times the event is equalled + number of times it is exceeded.]