Iranian Biology Olympiad Iranian Biology Olympiad Iranian Biology Olympiad (IrBO) is an annual multistage competition for Iranian high school students of the age of 17-18 in the field of biology. The first Iranian Biology Olympiad was launched under the auspices of the Ministry of Education, Iran in 1999. Since then, the four winners of the national competitions participate regularly yearly in the International Biology Olympiad (IBO), in which IrBO is a regular member and participant. In Iranian Biology Olympiad individuals compete for their achievements in both theory and practice. IrBO tried to challenge and stimulate gifted students to expand their talents and to
Return period interest and formula_5 is the counting rate. If the return period of occurrence is 1 in 234 years (formula_5 = 0.0043) then the probability of no occurrence in ten years is In a given period of "n" years, the probability of a given number "r" of events of a return period formula_5 is given by the binomial distribution as follows. In the limit of :formula_11, such that formula_12 then Take where Given that the return period of an event is 100 years, So the probability that such an event occurs "exactly once" in 10 successive years is: Return period is