Project 11.3

Find the probability that the 13th day of a randomly chosen month will be a Friday. (Hint: It is not correct to say that the probability is 1/7 because there are seven possible days in the week. In fact, it turns out that the 13th day of a month is more likely a Friday than any other day of the week.) Write a paper discussing this problem.

References:

William Bailey, "Friday-the-Thirteenth," The Mathematics Teacher, Vol. LXII, No. 5 (1969), pp. 363-364.
C. V. Heuer, Solution to Problem E1541 in American Mathematical Monthly, Vol. 70, No. 7 (1963), p. 759.
G. L. Ritter, et al, "An Aid to the Superstitious," The Mathematics Teacher, Vol. 70, No. 5 (1977), pp. 456-457.

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