The most accurate way would be the fourth answer, because to estimate 66% of 47 you need to round both as closely as possible. 66% rounds closest to 2/3, and 47 is closest to 48
Exact Surface Area = 378pi
Approximate Surface Area = 1186.92
The approximate surface area uses pi = 3.14
The units are cm^2 or "square cm".
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Work Shown:
SA = surface area of cylinder
SA = 2*pi*r^2 + 2*pi*r*h
SA = 2*pi*7^2 + 2*pi*7*20
SA = 2*pi*49 + 2*pi*140
SA = 2*49*pi + 2*140*pi
SA = 98pi + 280pi
SA = 378pi ..... exact surface area
SA = 378*3.14
SA = 1186.92 ..... approximate surface area
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Side note: The diameter 14 cuts in half to get the radius r = 7
Okay so CBE is a right angle which equals 90 degrees. CBD and DBE makes up CBE which is 23 degrees is part of CBD. So subtract CBE from CBD to get DBE which is 67 degrees.
2/5 divide -3/10 can be rewritten as 2/5 * - 10/3. Which is -20/15 = -4/3 = -1 1/3
well, let's say that the first solution is 7 liters and has "x" percent of acid, how much acid total in it? well, 7x, <u>keeping in mind that "x" is a decimal form</u>.
likewise, the second solution is 3 liters and has 15% acid, so how much acid is there in that one? (15/100) * 3 = 0.45, so
![\begin{array}{lcccl} &\stackrel{solution}{quantity}&\stackrel{\textit{\% of }}{amount}&\stackrel{\textit{liters of }}{amount}\\ \cline{2-4}&\\ \textit{1st solution}&7&x&7x\\ \textit{2nd solution}&3&0.15&0.45\\ \cline{2-4}&\\ mixture&10&0.29&2.9 \end{array}~\hfill \implies 7x~~ + ~~0.45~~ = ~~2.9 \\\\[-0.35em] ~\dotfill\\\\ 7x=2.45\implies x=\cfrac{2.45}{7}\implies x=0.35~\hfill \stackrel{\textit{converting to \%}}{0.35\cdot 100}\implies \stackrel{\%}{35}](https://tex.z-dn.net/?f=%5Cbegin%7Barray%7D%7Blcccl%7D%20%26%5Cstackrel%7Bsolution%7D%7Bquantity%7D%26%5Cstackrel%7B%5Ctextit%7B%5C%25%20of%20%7D%7D%7Bamount%7D%26%5Cstackrel%7B%5Ctextit%7Bliters%20of%20%7D%7D%7Bamount%7D%5C%5C%20%5Ccline%7B2-4%7D%26%5C%5C%20%5Ctextit%7B1st%20solution%7D%267%26x%267x%5C%5C%20%5Ctextit%7B2nd%20solution%7D%263%260.15%260.45%5C%5C%20%5Ccline%7B2-4%7D%26%5C%5C%20mixture%2610%260.29%262.9%20%5Cend%7Barray%7D~%5Chfill%20%5Cimplies%207x~~%20%2B%20~~0.45~~%20%3D%20~~2.9%20%5C%5C%5C%5C%5B-0.35em%5D%20~%5Cdotfill%5C%5C%5C%5C%207x%3D2.45%5Cimplies%20x%3D%5Ccfrac%7B2.45%7D%7B7%7D%5Cimplies%20x%3D0.35~%5Chfill%20%5Cstackrel%7B%5Ctextit%7Bconverting%20to%20%5C%25%7D%7D%7B0.35%5Ccdot%20100%7D%5Cimplies%20%5Cstackrel%7B%5C%25%7D%7B35%7D)
