5) Mario owns a plumbing business. He charges an hourly rate plus a onetime set up fee. His first job was 4 hours and he charged
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3 + 2 + 1 + 2 = 8, which is the amount of sweaters.
The probability of a brown sweater is 2 / 8 = 0.25
And the probability of a green sweater is 1 / 8 = 0.125.
Multiply the two probabilities together to get the probability of choosing brown then green:
0.25 * 0.125 = 0.03125.
To convert a decimal to fraction, you multiply the numerator and denominator, or in this case
Which can be simplified to:
Hope this helps.
Part A
Since order matters, we use the nPr permutation formula
We use n = 12 and r = 8
There are a little under 20 million different permutations.
<h3>Answer: 19,958,400</h3>Side note: your teacher may not want you to type in the commas
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Part B
In this case, order doesn't matter. We could use the nCr combination formula like so.
We have a much smaller number compared to last time because order isn't important. Consider a group of 3 people {A,B,C} and this group is identical to {C,B,A}. This idea applies to groups of any number.
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Another way we can compute the answer is to use the result from part A.
Recall that:
nCr = (nPr)/(r!)
If we know the permutation value, we simply divide by r! to get the combination value. In this case, we divide by r! = 8! = 8*7*6*5*4*3*2*1 = 40,320
So,
Not only is this shortcut fairly handy, but it's also interesting to see how the concepts of combinations and permutations connect to one another.
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<h3>Answer: 495</h3>