Suppose the test scores of students in a class are normally distributed with a mean of 85 and a standard deviation of 4. What is
1 answer:
Answer:
B
Step-by-step explanation:
Converting it to z, we can use the formula of z-score:
z-score =
Where
x is the value we are checking for (here, x = 79)
is the mean, which is 85
is the standard deviation, which is 4 now
<em>Let's plug the information into the formula and solve for the answer:</em>
<em></em>
<em />
<em>B is the correct answer.</em>
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Answer:
A. P(x>12 in 5 minutes)=0.0201
Step-by-step explanation:
Because we are working with a Poisson Distribution of probability, we need to get all the data needed. In a Poisson distribution is needed a constant called λ that symbolizes the mean data (6 calls) per unit of time (5 minutes), for this distribution λ=6/5.
Poisson probabilities work like this:
Remember y has to be an integer and the units of z must be the same unit of time used in λ. Now we are ready to solve this problem
A. The question is asking for the probability that in 5 minutes appear more calls than the phone-answering machine could answer (i.e P(x>12 in 5 minutes)). Because there are infinite numbers greater than 12, we are using this property of probabilities that´ll help us simplify the problem:
P(x>12 in 5 minutes)= 1 - P(x≤12 in 5 minutes)
Now we can use the following:
And you can find P(x=n in 5 minutes) for every n using a calculator or a computer, and finally add them to get
P(x≤12 in 5 minutes)= 0.9799
P(x>12 in 5 minutes)= 1-0.9799
This will be our answer
P(x>12 in 5 minutes)= 0.0201