2005-Fall-Midterm

# Fnd the mean and variance of y100 c find the

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Unformatted text preview: an and variance of Y100. (c) Find the probability that no more than 20 students obtain red balls on the 2nd and 3rd pick. (d) Suppose that only 10 boxes are considered. Find the probability that no more than 3 students obtain red balls on the 2nd and 3rd pick. (e) Suppose that after the first pick from the box, an extra ball of the same color is added to the box with probability ½. Otherwise no new ball is added. Given that there is no other change; for the 100 boxes, find the expected number of times an extra red ball is added to a box. (f) Suppose that 5 boxes are combined into one box. A student is then asked to take out 11 balls from the box at random. Find the probability that 7 are red. Question 2: [18 Marks] An urn has two coins. These coins each has two faces. The probabilities of landing heads (head faces up) for the two coins are: Coin 1: Coin 2: lands heads with probability ½ (coin has head on one side and tail on the other side) lands heads with probability 1 (coin has heads on both sides) ht tp :// ih om e. us t.h k/ ~c s_ gx x/ You select a coin at random (each coin has pro...
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## This note was uploaded on 02/27/2010 for the course ISOM ISOM111 taught by Professor Anthonychan during the Spring '09 term at HKUST.

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