9.286
[To change to mixed number, count the number of digits after the decimal point. There are 3 digits, so the denominator will be 1000]

Then we simplify the fraction
(286 ÷ 2)/(1000÷2) = 143/500
Therefore,

Dance class is at 3:45pm, because the dance studio would not be open that early.
If there are n people, each person could shake hands with 0 people, 1 person, 2 people,... on up to shaking hands with n − 1
people. Count how many different answers there are to asking the person the question "How many hands did you shake?" How many people are there? If the people are the pigeons, and the possible answers to the question "how many hands did you shake" are the holes, can we conclude anything yet? No? How about now noticing that at least one of the holes "I shook hands with noone" or "I shook hands with everyone" has to be empty... now what?
"Since there are more pigeons than holes there must be a hole with at least two pigeons in the same hole" Now, replace the word "pigeons" and "holes" with the appropriate terms for the context of your specific question, remember we are talking about people and number of handshakes they participated in.
Ya that's correct u got the right answer
The dimensions of the rectangular pen should be 15 by 20 feet and the maximum area is 1200 square feet.
Let the area be y .
Area = (base) × (height)
Base = 2x
Height = h
Let the area of the rectangular pens be y .
∴ y = 2xh
Perimeter of all the fencing = 4x+3h
∴ 4x+3h = 120
now we solve for h
3h = 120-4x
h = 40 - 4/3 x
Now we will substitute this value in the above first equation:
y = 2xh
or, y = 2x (40 - 4/3 x)
or, y = 80x - 8/3 x²
Now for the maximum area we have to find the first order differentiation of y
now,
dy /dx = 80 - 16/3 x
At dy/dx = 0 we get the value of x for which y is maximum.
80 - 16/3 x = 0
or, - 16/3 x = -80
or, x = 15 feet
Hence height = 40 - 4/3 x = 40 - 20 = 20feet
Maximum area = 2xh = 2×15×40 = 1200 square feet
The dimensions of the rectangular pen should be 15 by 20 feet and the maximum area is 1200 square feet.
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