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2 years ago

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Which equation could be used to find the cost of each Apple? 4x+3(0.89)=$7.15 , 3x+4(0.89)=$7.15 , $7.15-3x=0.89 , or 4x-3(0.89)

=$7.15

1 answer:

Dmitry_Shevchenko [17]2 years ago

5 0

Step-by-step explanation:

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The mean waiting time at the drive-through of a fast-food restaurant from the time the food is ordered to when it is received is

alexira [117]

Answer:

a) And if we replace we got: $\bar X= 78$

$s = 15.391$

b) $78-3.25\frac{15.391}{\sqrt{10}}=62.182$

$78-3.25\frac{15.391}{\sqrt{10}}=93.818$

So on this case the 99% confidence interval would be given by (62.182;93.818)

Step-by-step explanation:

Dataset given: 109 67 58 76 65 80 96 86 71 72

Part a

For this case we can calculate the sample mean with the following formula:

$\bar X = \frac{\sum_{i=1}^n X_i}{n}$

And if we replace we got: $\bar X= 78$

And the deviation is given by:

$s =\sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}}$

And if we replace we got $s = 15.391$

Part b

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=10-1=9$

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,9)".And we see that $t_{\alpha/2}=3.25$

Now we have everything in order to replace into formula (1):

$78-3.25\frac{15.391}{\sqrt{10}}=62.182$

$78-3.25\frac{15.391}{\sqrt{10}}=93.818$

So on this case the 99% confidence interval would be given by (62.182;93.818)

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2 years ago

Simplify: (3x^3+2x-3)-(4x^3-x^2+x

ad-work [718]

Answer: -x^3 - x^2 + 3x - 3

Glad I could help :D

Step-by-step explanation:

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2 years ago

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Which answer shows a reflection across the y-axis?

prohojiy [21]

The answer would be D.

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2 years ago

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Geometry.... homework..<br><br><br>

Nadusha1986 [10]

Answer:

-12 , -6

Step-by-step explanation:

- 7 - 5 = - 12

- 2 - 4 = - 6

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2 years ago

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The LCM of 2 numbers is 60 and 1 of the numbers is 7 less than the other number. What are the numbers?

Phoenix [80]

Let's represent the two numbers by x and y. Then xy=60. The smaller number here is x=y-7.

Then (y-7)y=60, or y^2 - 7y - 60 = 0. Use the quadratic formula to (1) determine whether y has real values and (2) to determine those values if they are real:

discriminant = b^2 - 4ac; here the discriminant is (-7)^2 - 4(1)(-60) = 191. Because the discriminant is positive, this equation has two real, unequal roots, which are
-(-7) + sqrt(191)
y = -------------------------
-2(1)

and

-(-7) - sqrt(191)
y = ------------------------- = 3.41 (approximately)
-2(1)

Unfortunately, this doesn't make sense, since the LCM of two numbers is generally an integer.

Try thinking this way: If the LCM is 60, then xy = 60. What would happen if x=5 and y=12? Is xy = 60? Yes. Is 5 seven less than 12? Yes.

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2 years ago