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2 years ago

HELP MEHHHHHHHHH. thanks.

Mathematics

2 answers:

jok3333 [9.3K]2 years ago

8 0

The Answer is A .....

maxonik [38]2 years ago

3 0

Answer:A

The mean is the average of all numbers, in this example it's to national averages which will have many numbers.

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Probability question (image included)

Alexandra [31]

Answer:

Step-by-step explanation:

3 0

3 years ago

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

Simplify: 6y + 5z + 8y – 3z

mezya [45]

Combine like terms. 6y + 8y is 14y. 5z - 3z is 2z. so the answer is 14y + 2z.

4 0

3 years ago

Read 2 more answers

Please help me evaluate the expression 10a + 7 if a =1/5

sattari [20]

Answer:

Step-by-step explanation:

10a+7

10(1/5) + 7

2+7

6 0

2 years ago

Rewrite the radical as a rational exponent. the fourth root of 7 to the fifth power 7 to the 5 over 4 power 720 7 7 to the 4 ove

adoni [48]

I don't understand what you mean by "720 7 7 to the 4 over 5 power", but for "the fourth root of 7 to the fifth power 7 to the 5 over 4 power" it would be 7^5 (seven to the power of 5)

3 0

3 years ago