Answer:
12% decrease
Step-by-step explanation:
50 - 44 = 6
6/50 = 0.12 or 12% decrease
You would have to go 25 times to make it worth getting option b
If x represents the width of the poster (including borders), the area of the finished poster can be written as
.. a = x*(390/(x -10) +8)
.. = 8x +390 +3900/(x -10)
Then the derivative with respect to x is
.. da/dx = 8 -3900/(x -10)^2
This is zero at the minimum area, where
.. x = √(3900/8) +10 ≈ 32.08 . . . . cm
The height is then
.. 390/(x -10) +8 = 8 +2√78 ≈ 25.66 . . . . cm
The poster with the smallest area is 32.08 cm wide by 25.66 cm tall.
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In these "border" problems, the smallest area will have the same overall dimension ratio that the borders have. Here, the poster is 10/8 = 1.25 times as wide as it is high.
Given :-
- y varies directly as x, and y=14 when x=4.
To Find :-
- the value of y when x=9 .
Solution :-
<u>A</u><u>c</u><u>c</u><u>o</u><u>r</u><u>d</u><u>i</u><u>n</u><u>g</u><u> </u><u>t</u><u>o</u><u> </u><u>Q</u><u>u</u><u>e</u><u>s</u><u>t</u><u>i</u><u>o</u><u>n</u><u> </u><u>,</u>
<u>When</u><u> </u><u>y</u><u> </u><u>=</u><u> </u><u>1</u><u>4</u><u> </u><u>a</u><u>n</u><u>d</u><u> </u><u>x</u><u> </u><u>=</u><u> </u><u>4</u><u> </u><u>,</u>
<u>W</u><u>h</u><u>e</u><u>n</u><u> </u><u>x</u><u> </u><u>=</u><u> </u><u>9</u><u> </u><u>,</u>
- y = 7/2*9
- y = 63/2
- y = 31.5