Question

# In a sample of 100 students taken randomly from QU, 70 of them have Twitter account,...

In a sample of 100 students taken randomly from QU, 70 of them have Twitter account, 80 have Facebook account, and 60 of them have both accounts. If a student is randomly selected:

The probability that he/she has at least one account is
The probability that he/she has no Twitter account is
The probability that he/she has Twitter account only is
The probability that he/she has either Twitter or Facebook account but not both is

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About 60% of the car accidents in a given highway road are due to exceed of the limited high speed. If a study will investigate 10 cars accidents

The probability that none is due to exceed of the limited high speed is
The probability that 5 exact accidents are due to exceed of the limited high speed is
The probability that at least 1 car accident is due to exceed of the limited high speed is
The probability that at most 1 car accident is due to exceed of the limited high speed is
The expected number of car accidents due to exceed of the limited high speed is

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A sales firm receives on average three calls per hour on its toll-free number. For any given hour, find the probability that it will receive the following:

at most 3 calls.
at least 3 calls.
five or more calls.
between 1 and 4 calls in 2 hours.
Find the average number of calls.
Find the standard deviation of number of calls.

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We select randomly one number from the set S={-2, 0, 1, 3}. Let X be the obtained number. The variance of the random variable X is

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The table shows the results of a survey of students in two STAT 101 classes

Do you Have class at 8am?   Did you watch more than one hour of TV last night?
Yes   No
Yes   11   6
No   13   10

What is the probability that a student watch more than one hour TV or has no 8am class?

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