Let X be chickens
Let Y be pigs,
then x+y=13
the animals have 2x+4y legs,
so 2x+4y=40
The system of the equations
[X+y=13
[2x+4y=40
Divide the second equation by 2
[x+y=13
[x+2y=20
subtract the first equation from the second one
y=20-13
y-7 pigs
substitute y=7 into the first equation
x+7=13
x=13-7
x=6 chickens
Considering the probabilities of getting each question right, his expected score for the test is 90.8.
<h3>How to find Joe's expected score?</h3>
Joe's expected score is given by the sum of the expected score for each question.
We have that:
- He is sure of 12 answers, hence for each he expects 6 points.
- He randomly guesses on 9 problems, hence he is expected to have a 1/5 probability of earning 6 on them.
- For the other 4 problems, he has a 1/3 probability of earning 6 on them, as he will guess from 3 options as he eliminated 2.
Hence his expected score is given by:
E(X) = 12 x 6 + 9 x 1/5 x 6 + 4 x 1/3 x 6 = 90.8.
More can be learned about the expected score of a distribution at brainly.com/question/13617733
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To the nearest cent it would cost $29.99
You cannot factor out a coefficient in this expression, because 9 and 8 do not have a common factor besides 1.
