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2 years ago

I NEED HELPPP AHHH!!!!!!

Mathematics

1 answer:

IRISSAK [1]2 years ago

5 0

Answer:

the answer is B there is no other possible answer that you can put.

Step-by-step explanation:

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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.

4 0

3 years ago

which polynomials are in standard form? A. t^4-1 B. -2t^2+3t+4 C. 4t-7 D. None of The Above Choose all answers that apply

Nikitich [7]

Answer:

B. -2t^2+3t+4

Step-by-step explanation:

The standard form as

ax^2 + bx + c

Option B meets that requirement, even though it has a '-' in front

5 0

3 years ago

What is Add and Simply 7/4 + 5/6 =

Pani-rosa [81]

Simple, first find a common denominator, 24.

So,

7/4*6= 42/24
and
5/6*6=30/24

Then just add,

42/24
+
30/24

Making it 72/24.

72/24=3

Thus, your answer is, 3.

5 0

2 years ago

Which shows how to find the value of this expression when X=-2 and Y = 5?

Anna35 [415]

Answer:

just try to plug in the awnsers you have

Step-by-step explanation:

text me cutie <3

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3 years ago

What is the sum of the infinite geometric series with a1=42 and r=6/5?

Cerrena [4.2K]

This infinite sum is given by

a
S = ------ but ONLY if r<1. Here, r>1, so the infinite sum does not exist.
1-r

8 0

3 years ago