Unformatted text preview: MATH 218 FINAL EXAMINATION
December 17, 2003
Professors: J. Colwell, F. Lin, K. Styrkas, E. Verona, Z. Vorel.
Problem 1. A random sample of 50 purchases at a department store produced the following contingency table for the method of payment and the size of the purchase:
Cash Credit card Debit card Under $30 5 2 2 $30 to $100 2 10 9 Over $100 1 12 7 (a) Given that a purchase was made with a debit card, ﬁnd the probability that it
was at least $30.
(b) Given that a credit card purchase was at least $30, ﬁnd the probability that it
was over $100.
(c) Find the probability that a purchase was under $30.
(d) Find the probability that a purchase was paid by...
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