PLEASE HELP, What is the annual interest rate she is earning on her deposit?

How many pounds of a 15% copper alloy must be mixed with 700lb of a 30% copper alloy to maybe a 25.5% copper alloy

lisov135 [29]

Answer:

$300\; \rm lb$ .

Step-by-step explanation:

Let $x$ represent the mass (in pounds) of that $15\%$ copper alloy required, such that the final mixture would contain $25.5\%$ copper by mass.

Consider: if $x$ pounds of that $15\%$ copper alloy is mixed with $700$ pounds that $30\%$ copper alloy, what would be the mass of copper in the mixture?

Mass of copper in $x$ pounds of that $15\%$ copper alloy: $(0.15\, x)\; \rm lb$ .
Mass of copper in $700$ pounds of that $30\%$ copper alloy: $700 \times 0.30 = 210\; \rm lb$ .

Therefore, the mixture would contain $(210 + 0.15\, x) \; \rm lb$ of copper.

The mass of that mixture would be $(700 + x)\; \rm lb$ . The mass fraction of copper in that mixture would be:

$\displaystyle \frac{(210 + 0.15\, x)\; \rm lb}{(700 + x)\; \rm lb} \times 100\%$ .

This ratio is supposed to be equal to $25.5\%$ . These two pieces of equations combine to give an equation about $x$ :

$\displaystyle \frac{(210 + 0.15\, x)\; \rm lb}{(700 + x)\; \rm lb} \times 100\% = 25.5\%$ .

$\displaystyle \frac{210 + 0.15\, x}{700 + x} = 0.255$ .

Simplify and solve for $x$ :

$210 + 0.15\, x= 0.255\, (700 + x)$ .

$(0.255 - 0.15)\, x= 210 - 0.255 \times 700$ .

$\displaystyle x = \frac{210 - 0.255 \times 700}{0.255 - 0.15} = 300$ .

Therefore, $300\; \rm lb$ of that $15\%$ alloy would be required.

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Mia is making costumes for a play. Each costume needs 3 7/9 yards of fabric. If Mia is making 6 costumes, how much fabric does s

mihalych1998 [28]

If she is making 6 costumes that need 3 7/9 yards each, the equation would be 6 x 3 7/9.

The answer to that equation would be 22 2/3.

How to get the answer:
3 x 6 = 18
7 x 6 = 42 (the seven is from the 7/9)
42/9 = 4 2/3

then add the eight teen and the 4 2/3 and you get 22 2/3.

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3 years ago

Jabari is thinking of three numbers. The greatest number is twice as large as the least number. The middle number is three more

RUDIKE [14]

Answer:

18,21,36

Step-by-step explanation:

You can use Algebra to solve it x+x+3+2x=75 or 4x+3=75 will give you the answer 18
18 then plus 3 is 21
so 18 plus 21 is 39
Then the greatest number is 18x2=36
39+36=75

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Which one of the following items does not appear under the heading 'equity and reserves' on a company

statement of financial position?

A Share premium account

B Retained earnings

C Revaluation surplus

D Loan stock

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3 years ago

How to simplify I^12

butalik [34]

Answer:

I can't be simplified because it is already in it's simplified form.

Step-by-step explanation:

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