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3 years ago

I need the answer this is the last question

Mathematics

2 answers:

svp [43]3 years ago

7 0

Answer:8

Step-by-step explanation:

max2010maxim [7]3 years ago

4 0

Answer:

Hope this helps

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

A mechanic buys $14.56 worth of parts from a supplier. If he pays for the parts with a $20 bill, how much change will he receive

GarryVolchara [31]

$20-$14.56=$5.44

The mechanic would get $5.44 back as change.

8 0

3 years ago

Read 2 more answers

I need help on this

sweet [91]

So basically you would take you your m which is 339 degrees greater than 3 so you would divide 339 by 3 and get 113 so your m= 113 degrees so for example the first question would be m<1 = 113 and so on so you would multiply 113 by the number it is greater than

6 0

3 years ago

Compute each sum below. If applicable, write your answer as a fraction.

Alex777 [14]

Answer:

First equation is -425

Second equation is 11.25

Step-by-step explanation:

First equation we can write as

$\sum_{i=0}^7 5 \times (-2)^i$

computing

When i=0 -> $5 \times (-2)^0 =5$

When i=1 -> $5 \times (-2)^1 = -10$

...

When i=7 -> $5 \times (-2)^7 = --640$

then replacing each term we have

$5 + (-10) + ( 20) + ( -40) + (80) +( -160) + 320 + (-640) = -425$

For the second equation we'll have 9 terms, solving in a similar fashion

When i=1 -> $\frac{1}{4}1=0.25$

When i=2 -> $\frac{1}{4}2=0.50$

When i=3 -> $\frac{1}{4}3=0.75$

...

When i=9 -> $\frac{1}{4}9=2.25$

So we have 0.25 + 0.50 + 0.75 + 1.00 + 1.25 + 1.50+ 1.75 +2.00 +2.25

4 0

4 years ago

A vacant city lot is being turned into a neighborhood garden. The neighbors want to fence in a triangular section of the lot and

ozzi

9514 1404 393

Answer:

17 ft, 27 ft, 20 ft

Step-by-step explanation:

Let s represent the length of the shortest side. The the longest side is (2s-7) and the third side is (s+3). The perimeter is the sum of the side lengths:

64 = s +(2s -7) +(s +3)

64 = 4s -4 . . . . . . . . . . . collect terms

16 = s -1 . . . . . . . . . . divide by 4

17 = s . . . . . . . . . add 1

2s -7 = 2·17 -7 = 27 . . . . . the length of the longest side

s +3 = 17 +3 = 20 . . . . . . . the length of the third side

The side lengths are 17 feet, 27 feet, and 20 feet.

8 0

3 years ago