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Linyi Yimo 20 16 Mathematics
(i) The median of each set of data can be used to estimate the average score of the sampled students,

. x=45×0.05+55×0. 15+65×0.2+75×0.3+85×0.25+95×0.05═72

So it is estimated that the average score of this exam is 72.

(2) The number of all possible basic results of the numbers 95, 96, 97, 98, 99 and 100 is C62= 15, and there are 15 results.

The number of students with [90, 100] is 0.005× 10×80=4.

These two figures are just the basic results of two students' math scores, C42=6.

The probability that two numbers are exactly the math scores of two students is p = 6 15 = 25.