A coin is flipped four times. X is the number of times it will land with a head up.

Which statement is true about this situation?


The variable X does not have a binomial distribution because  P(success) is not constant.

The variable X does not have a binomial distribution because there are more than two possible outcomes.

The variable X has a binomial distribution. P(success)=0.25; number of trials = 4

The variable X has a binomial distribution. P(success)=0.5P(success)=0.5; number trials = 4



The probability that traffic lights on a certain road will be green is 0.6. When a driver on that road approaches two traffic lights in a row, X is the number of traffic lights that are green.

What is P(X=1)? (Written as a decimal).

 Mar 8, 2018

Sentences 1 and 2 are wrong since P is constant (with heads and tails being equal outcomes) and those are the only 2 outcomes. Sentence 4 should be the right answer since there are 4 trials and there are only two outcomes (with the probability of 1/2 being chosen).



There are 2 traffic lights. If one is green and one is not, we need to multiply the probability that one is green and the probability that one is not.


.6*.4 = 0.24

 Mar 11, 2018

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