CFA Practice Question

There are 434 practice questions for this study session.

CFA Practice Question

Which of the following is not a binomial experiment?

A. Flipping a coin 3 times and letting x count the number of heads obtained.
B. Rolling a die 3 times and letting x count the numbers of 2s obtained.
C. Randomly selecting a ball (with replacement) three times from a jar containing 1, 2, 2, 5, 6, and 7, and letting x count the number of 2s obtained.
D. Randomly selecting 3 balls from a jar containing balls numbered 1, 2, 2, 5, 6, 7 and letting x count the number of 2s obtained.
Correct Answer: D

For "randomly selecting 3 balls from a jar containing balls numbered 1, 2, 2, 5, 6, 7 and letting x count the number of 2s obtained," we do not have independent events. So, this is not a binomial experiment. We can find the probability distribution for random variable x using a tree diagram (we can not use the binomial formula).

User Contributed Comments 10

User Comment
wanger what's 2s?
songshow what is difference with B.C.D
tengo only d changes the experiment so that it is no longer independent. Since the 3 balls are not replaced in the jar after each trial the probabilities for the second trial are not equal to the probabilities of the first trial
danlan It's similar to 3
chamad Another way to get answer D is that there is only two 2s. So D is impossible as you'll never get 3 balls!
Meka76 I like chamad's answer...thanks!
magicchip Key is no replacement.
bundy Replacement is key
mjwoulf chamad - you can still draw 3 balls, there is just a 0% chance of 3 balls being 2s. Yup, replacement.
praj24 Two Twos, nah!?!
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