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2 years ago

Is 8/24 = 21/63 a proportion

Mathematics

2 answers:

ira [324]2 years ago

7 0

Step-by-step explanation:

8/24 = 21/63 = 1/3

yes it's a proportion

Flura [38]2 years ago

5 0

Yes it is a proportion

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An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in Texas. He believes that

Llana [10]

Answer:

We need a sample size of at least 170.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.8}{2} = 0.1$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.1 = 0.9$ , so $z = 1.28$

Now, find M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population(square root of the variance) and n is the size of the sample.

How large of a sample would be required in order to estimate the mean per capita income at the 80%80% level of confidence with an error of at most $0.52$ 0.52?

A sample size of at least n, in which n is found when $M = 0.52, \sigma = \sqrt{34.81} = 5.9$

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.58 = 1.28*\frac{5.9}{\sqrt{n}}$

$0.58\sqrt{n} = 1.28*5.9$

$\sqrt{n} = \frac{1.28*5.9}{0.58}$

$(\sqrt{n})^{2} = (\frac{1.28*5.9}{0.58})^{2}$

$n = 169.5$

Rounding up

We need a sample size of at least 170.

6 0

3 years ago

The expression 20l + 25g - 10, gives the number of dollars that Josie makes from mowing l lawns and raking g gardens. How many d

tiny-mole [99]

20 • 3=60, 25 • 4=100. 60+100=160. 160-10=150. Josie makes $150.

3 0

3 years ago

Read 2 more answers

Rylee shopped at a clothing store, where she spent $36.50 plus 8% tax. Then, she spent $25 to refuel her car at the gas station.

inn [45]

Answer: The net change to her banking account balance is $83.22.

Step-by-step explanation:

Hi to answer this question we have to analyze the information given:

She spent $36.50 plus 8% tax. ( to calculate the tax amount we have to multiply the cost by the percentage in decimal form)

36.50 x (8/100) =$2.92 (value of tax)

Adding to the original cost

36.50+2.92 = $39.42

Then, she spent $25 to refuel her car at the gas station.

39.42 +25 = $64.42

She bought groceries worth $23.50. At the grocery checkout, she handed over a coupon for a 20% discount on her purchase

23.50 x (20/100) = 4.7 (amount of discount)

Subtracting to the purchase

23.50 -4.7= $18.8

Finally, adding to the total cost.

64.42 +18.8 = $83.22

4 0

3 years ago

Find an equation of the tangent plane to the surface z=ln(x-6y) at the point(7,1,0)

expeople1 [14]

The tangent plane equation of tangent plane is

z = x - 6y -1

This is further explained below.

What is the equation of the tangent plane to the surface z=ln(x-6y) at the point(7,1,0)?

Generally, Given surface is z = ln(x − 6y) ,

Given point is $(x_0, y_0 , z_0)$ = (7, 1, 0)

partially differentiating with respect to x

== >zx = [1/(x - 6y)] (1) = 1/(x - 6y)

zx (7 , 1 , 0) = 1/(7 - 6(1)) = 1

Partially differentiating with respect to y

zy = [1/(x - 6y)] (-6)

zy = -6/(x - 6y)

zy(7 , 1 , 0) = -6/(7 - 6(1)) = -6

Equation of tangent plane is z - $z_0$ = zx(x - $x_0$ ) + zy(y - $y_0$ )

z - 0 = 1(x - 7) + (-6)(y - 1)

z = x - 7 -6y + 6

z = x - 6y -1

In conclusion, equation of tangent plane is z = x - 6y -1