Question
coin a is weighed so that the probability of throwing head is 2/3. coin b is weighed so that the probability of throwing a head is 1/4. coin a is thrown twice and coin b is thrown once.
(I)show that the probability of obtaining exactly 1 head and 2 tails is 13/16
(I)show that the probability of obtaining exactly 1 head and 2 tails is 13/16
Answers
Reiny
make a list of the possible outcomes of your event
under the headings
a a b
TTH --- (1/3)(1/3)(1/4) = 1/36
THT --- (1/3)(2/3)(3/4) = 6/36
HTT --- (2/3)(1/3)(3/4) = 6/36
total = 1/36 + 6/36 + 6/36) = 13/36
mmmhhh, did I miss something ?
under the headings
a a b
TTH --- (1/3)(1/3)(1/4) = 1/36
THT --- (1/3)(2/3)(3/4) = 6/36
HTT --- (2/3)(1/3)(3/4) = 6/36
total = 1/36 + 6/36 + 6/36) = 13/36
mmmhhh, did I miss something ?