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3 years ago

9

Marco needs $57 to buy new basketball shoes. If Marco earns $3 per day working and already has $12 saved, which equation shows h

ow many days Marco must work before he can afford the shoes?

2 answers:

masya89 [10]3 years ago

7 0

Answer:

(57-12)3/x=15 days

x=57-12

Montano1993 [528]3 years ago

6 0

Answer:

57=12+3d

d=number of days worked

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Georgia [21]

Answer:

the answer is i dont know

6 0

2 years ago

My brother wants to estimate the proportion of Canadians who own their house.What sample size should be obtained if he wants the

AVprozaik [17]

Answer:

a) $n=\frac{0.675(1-0.675)}{(\frac{0.02}{1.64})^2}=1475.07$

And rounded up we have that n=1476

b) $n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.64})^2}=1681$

And rounded up we have that n=1681

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

If solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

Part a

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by $\alpha=1-0.9=0.1$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=\pm 1.64$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.02$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.675(1-0.675)}{(\frac{0.02}{1.64})^2}=1475.07$

And rounded up we have that n=1476

Part b

For this case since we don't have a prior estimate we can use $\hat p =0.5$

$n=\frac{0.5(1-0.5)}{(\frac{0.02}{1.64})^2}=1681$

And rounded up we have that n=1681

8 0

3 years ago

Chau's Coffee Shop makes a blend that is a mixture of two types of coffee. Type A coffee costs Chau $5.50 per pound, and type B

Anettt [7]

84 pounds of Type B coffee is used

<em><u>Solution:</u></em>

Let "x" be the pounds of type A coffee

Let "y" be the pounds of type B coffee

Cost per pound of type A = $ 5.50

Cost per pound of Type B = $ 4.20

<em><u>This month, Chau made 143 pounds of the blend</u></em>

x + y = 143

x = 143 - y -------- eqn 1

<em><u>For a total cost of $677.30. Thus we frame a equation as:</u></em>

pounds of type A coffee x Cost per pound of type A + pounds of type B coffee x Cost per pound of Type B = 677.30

$x \times 5.50 + y \times 4.20 = 677.30\\\\5.5x + 4.2y = 677.30 -------- eqn 2$

<em><u>Let us solve eqn 1 and eqn 2</u></em>

<em><u>Substitute eqn 1 in eqn 2</u></em>

$5.5(143-y) +4.2y = 677.30\\\\786.5 -5.5y + 4.2y = 677.30\\\\5.5y - 4.2y = 786.5 - 677.30\\\\1.3y = 109.2\\\\Divide\ both\ sides\ by\ 1.3\\\\y = 84$

Thus 84 pounds of Type B coffee is used

8 0

3 years ago

Pleaseee help I keep getting undefined

Zanzabum

Answer:

Second option "B. 4" is the correct choice.

Step-by-step explanation:

$(-8)^{\frac{2}{3}}\\\\\mathrm{Apply\:exponent\:rule}:\quad \left(-a\right)^{\frac{m}{n}}=\left(-1\right)^{\frac{m}{n}}\left(a\right)^{\frac{m}{n}}\\\\=\left(-1\right)^{\frac{2}{3}}\cdot \:8^{\frac{2}{3}}\\\\=1\cdot \:8^{\frac{2}{3}}\\\\=8^{\frac{2}{3}}\\\\=\left(2^3\right)^{\frac{2}{3}}=2^{3\cdot \frac{2}{3}}=2^2\\\\=4$

Best Regards!

5 0

4 years ago

Read 2 more answers

Please answer the question from the attachment.

Feliz [49]

If Keith pays $70, we know that $14 would have been paid, regardless of how long he rented a bike for. 70 - 14 = 56, so $56 would have been paid depending on the time he rented the bike for. If the cost per hour is $7, then the number of hours Keith rented the bike for is just $56 ÷ $7 per hour, which equals 8 hours.

Keith rented the bike for 8 hours.

Hope this helps!

5 0

3 years ago