Browsing as Guest. Progress, bookmarks and attempts are disabled.
Log in to track your work.
Nov 2017 p62 q4
3021
A fair tetrahedral die has faces numbered 1, 2, 3, 4. A coin is biased so that the probability of showing a head when thrown is \(\frac{1}{3}\). The die is thrown once and the number \(n\) that it lands on is noted. The biased coin is then thrown \(n\) times. So, for example, if the die lands on 3, the coin is thrown 3 times.
Find the probability that the die lands on 4 and the number of times the coin shows heads is 2. [3]
Find the probability that the die lands on 3 and the number of times the coin shows heads is 3. [1]
Find the probability that the number the die lands on is the same as the number of times the coin shows heads. [3]
Solution
(i) The probability that the die lands on 4 is \(\frac{1}{4}\). The probability of getting exactly 2 heads in 4 coin tosses is given by the binomial probability formula: