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3 years ago

This is all I know what to do any help?

Mathematics

1 answer:

svetoff [14.1K]3 years ago

4 0

You can multiply the second equation by -2

-5x + y = 15 everything by -2

10x - 2y = -30

now you can solve them

2x + 2y = -6
10x - 2y = -30

y cancels

2x= -6
10x = -30

12x = -36
/12. /12

x = -3

now to solve for y you substitute x for -3

-5(-3) + y = 15
15 + y = 15
-15 -15

y= 0

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3 years ago

At the candy shop, Ameenah sells chocolate covered raisins, c, for $1.50 per pound, and peanuts, p, for $1.20 per pound. Ameenah

insens350 [35]

Answer:

10 pounds of raisins and 10 pounds of peanuts.

Step-by-step explanation:

Let c represent the pounds of chocolate covered raisins.

Let p represent the pounds of peanuts.

We know that the raisins cost $1.50 per pound and the peanuts cost $1.20 per pound.

Ameenah wants to make 20 pounds of a mixture of the raisins and peanuts that sells for 1.35 a pound. So, we can write the following expression:

$1.5c+1.2p$

This represents the cost given c pounds of raisins and p pounds of peanuts.

Ameenah wants to combine c and p to make them 1.35 per pound. In other words, the expression must equal:

$1.5c+1.2p=1.35(c+p)$

We also know that she wants to make 20 pounds. So, c plus p must total 20. Therefore:

$c+p=20$

We now have the system of equations:

$\left\{ \begin{array}{ll} 1.5c+1.2p=1.35(c+p) \\ c+p=20\end{array}$

First, since we know that c+p is 20, we can substitute that into the first equation.

Second, let's subtract p from both side for the second equation to isolate a variable. So:

$c=20-p$

Let's now substitute this into the first equation:

$1.5(20-p)+1.2p=1.35(20)$

Distribute:

$30-1.5p+1.2p=27$

Combine like terms:

$-0.3p+30=27$

Subtract 30 from both sides:

$-0.3p=-3$

Divide both sides by -0.3. So, the amount of peanuts needed is:

$p=10$

10 pounds of peanuts is needed.

This means that 20-10 or 10 pounds of raisins is needed.

5 0

3 years ago

Read 2 more answers

A sample size must be determined for estimating a population mean given that the confidence level is % and the desired margin o

Sauron [17]

Complete Question

The complete question is shown on the first uploaded image

Answer:

$n =290$

$n =129$

The correct option is D

Step-by-step explanation:

From the question we are told that

The margin of error is $E = 0.23$

The largest value is k = 15

The smallest value is u = 7

From the question we are told the confidence level is 95% , hence the level of significance is

$\alpha = (100 - 95 ) \%$

=> $\alpha = 0.05$

Generally from the normal distribution table the critical value of $\frac{\alpha }{2}$ is

$Z_{\frac{\alpha }{2} } = 1.96$

Generally population standard deviation estimate is mathematically represented as

$\sigma = \frac{Range }{4}$

Here the Range is mathematically represented as

$Range = k - u$

=> $Range = 15 - 7$

=> $Range = 8$

=> $\sigma = \frac{8 }{4}$

=> $\sigma = 2$

Generally the sample size is mathematically represented as

$n = [\frac{Z_{\frac{\alpha }{2} } * \sigma }{E} ] ^2$

=> $n = [1.96 * 2 }{0.23} ] ^2$

=> $n =290$

Generally to obtain a conservatively small sample size the population standard deviation estimate becomes

=> $\sigma = \frac{Range }{6}$

=> $\sigma = \frac{8 }{6}$

=> $\sigma =1.333$

Generally the conservatively small sample size is mathematically evaluated as

$n = [\frac{Z_{\frac{\alpha }{2} } * \sigma }{E} ] ^2$

=> $n = [1.96 * 1.333 }{0.23} ] ^2$

=> $n =129$

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3 years ago

Find the arc length for arcs of circles as follows:

Sauron [17]

Answer:

≈ 11.78 in

Step-by-step explanation:

The arc length is calculated as

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= $\frac{15\pi }{4}$

≈ 11.78 in ( to 2 dec. places )

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