The mean checkout time in the express lane of a large grocery store is 2.7 minutes, and the standard deviation is 0.6 minutes. T
he distribution of checkout times is non-normal (for one thing, it can be a lot longer than 2.7 minutes, but it can only be so short). (a) What is the probability that a randomly-selected customer will take less than 3 minutes?
1 answer:
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Answer:
a)
b)
Step-by-step explanation:
Previous concepts
The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".
Solution to the problem
Part a
Let X the random variable "number of people math phobicmath phobic" , on this case we now that the distribution of the random variable is:
The probability mass function for the Binomial distribution is given as:
Where (nCx) means combinatory and it's given by this formula:
And we want this probability:
If we use the probability mass function we got:
Part b
For this case we want this probability:
We can find first this probability