4. How many ways can you shuffle 7 songs in a playlist?
2 answers:
Answer:
5040
Step-by-step explanation:
There are 7 options for the 1st song, 6 options for the 2nd song, 5 options for the 3rd song, 4 options for the 4th song, 3 options for the 5th song, 2 options for the 6th song, and 1 option for the 7th song. We get:
(<em>Note: when you have a number n, where it is multiplied by every number until one (ex. 7. 7*6*5*4*3*2*1), then the number in the result is n! (n factorial). So we get that 7*6*5*4*3*2*1 is 7! is 7 factorial. So 5040 is 7! </em>)
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Answer:
E. 0.11
Step-by-step explanation:
We have these following probabilities:
A 10% probability that a person has the flu.
A 90% probability that a person does not have the flu, just a cold.
If a person has the flu, a 99% probability of having a runny nose.
If a person just has a cold, a 90% probability of having a runny nose.
This can be formulated as the following problem:
What is the probability of B happening, knowing that A has happened.
It can be calculated by the following formula
Where P(B) is the probability of B happening, P(A/B) is the probability of A happening knowing that B happened and P(A) is the probability of A happening.
In this problem, we have that:
What is the probability that a person has the flu, given that she has a runny nose?
P(B) is the probability that a person has the flu. So P(B) = 0.1.
P(A/B) is the probability that a person has a runny nose, given that she has the flu. So P(A/B) = 0.99.
P(A) is the probability that a person has a runny nose. It is 0.99 of 0.1 and 0.90 of 0.90. So
What is the probability that this person has the flu?
The correct answer is:
E. 0.11