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Vladimir79 [104]

3 years ago

5

Uma wants to buy a video game system for $400. She has $50 and is saving $25 each week. Solve the equation 25w + 50 = 400 to fin

d how many weeks w it will take Uma to save enough to buy the system.
16 weeks

13 weeks

14 weeks

15 weeks

r2 = Aπ

r2 = A – π

1 answer:

pav-90 [236]3 years ago

4 0

Answer:

14 weeks

Step-by-step explanation:

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A normal population has a mean of 19 and a standard deviation of 5.

dangina [55]

Answer:

a) $Z = 1.2$

b) 38.49% of the population is between 19 and 25.

c) 34.46% of the population is less than 17.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by

$Z = \frac{X - \mu}{\sigma}$

After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X. If we need to find the probability that the measure is larger than X, it is 1 subtracted by this pvalue.

For this problem, we have that

A normal population has a mean of 19 and a standard deviation of 5, so $\mu = 19, \sigma = 5$ .

(a) Compute the z value associated with 25

This is Z when $X = 25$

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{25 - 19}{5}$

$Z = 1.2$

(b) What proportion of the population is between 19 and 25?

This is the pvalue of Z when $X = 25$ subtracted by the pvalue of Z when $X = 19$ .

X = 25 has $Z = 1.2$ , that has a pvalue of 0.8849.

X = 19 has $Z = 0$ , that has a pvalue of 0.5000.

So 0.8849-0.500 = 0.3849 = 38.49% of the population is between 19 and 25.

(c) What proportion of the population is less than 17?

This is the pvalue of Z when $X = 17$

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{17 - 19}{5}$

$Z = -0.40$

$Z = -0.40$ has a pvalue of 0.3446.

This means that 34.46% of the population is less than 17.

7 0

3 years ago

What is 825 divided by 7

grandymaker [24]

825 ÷ 7 = <span>117.857142857
hope i helped!!!!!</span>

6 0

3 years ago

Match the pairs of equations that represent concentric circles. Tiles

Darina [25.2K]

I will explain you and pair two of the equations as an example to you. Then, you must pair the others.

1) Two circles are concentric if they have the same center and different radii.

2) The equation of a circle with center xc, yc, and radius r is:

(x - xc)^2 + (y - yc)^2 = r^2.

So, if you have that equation you can inmediately tell the coordinates of the center and the radius of the circle.

3) You can transform the equations given in your picture to the form (x -xc)^2 + (y -yc)^2 = r2 by completing squares.

Example:

Equation: 3x^2 + 3y^2 + 12x - 6y - 21 = 0

rearrange: 3x^2 + 12x + 3y^2 - 6y = 21

extract common factor 3: 3 (x^2 + 4x) + 3(y^2 -2y) = 3*7

=> (x^2 + 4x) + (y^2 - 2y) = 7

complete squares: (x + 2)^2 - 4 + (y - 1)^2 - 1 = 7

=> (x + 2)^2 + (y - 1)^2 = 12 => center = (-2,1), r = √12.

equation: 4x^2 + 4y^2 + 16x - 8y - 308 = 0

rearrange: 4x^2 + 16x + 4y^2 - 8y = 308

common factor 4: 4 (x^2 + 4x) + 4(y^2 -8y) = 4*77

=> (x^2 + 4x) + (y^2 - 2y) = 77

complete squares: (x + 2)^2 - 4 + (y - 1)^2 - 1 = 77

=> (x + 2)^2 + (y - 1)^2 = 82 => center = (-2,1), r = √82

Therefore, you conclude that these two circumferences have the same center and differet r, so they are concentric.

5 0

3 years ago

How would you write 105% as a decimal?

kondor19780726 [428]

105% as a decimal would be 1.05 in decimal form

4 0

3 years ago

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A=960 rounded to the nearest 10 <br> b=89.0 rounded to 1 DP <br> Find the minimum (to 2 DP) of a÷b

astraxan [27]

Step-by-step explanation:

a÷b=960÷89=10.78651685=10.79 or 17.8

3 0

3 years ago

Read 2 more answers