Suppose hundred denominations are n, hence, 500 hundred and 1000 denominations will also be n.
total notes = n+n+n = 3n
number of ways of selecting one 1000 denomination out of 1000 denominations = nC1 = n
number of ways of selecting one denomination out of all available denominations = 3nC1 = 3n
hence, probability of selecting one 1000 denomination = n/(3n) = 1/3 = 0.3333 Ans.
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