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3 years ago

Take 9 from 6, 10 from 9, 50 from 40 and leave 6. What is the answer?

Mathematics

1 answer:

tekilochka [14]3 years ago

7 0

Take 9 from 6 = -3
Take 10 from 9 = -1
Take 50 from 40 and leave 6 = -4

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A researcher wishes to estimate the percentage of adults who support abolishing the penny. What size sample should be obtained i

Scorpion4ik [409]

Answer:

a) We need a sample size of at least 3109.

b) We need a sample size of at least 4145.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

The margin of error is:

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

99% confidence level

So $\alpha = 0.01$ , z is the value of Z that has a pvalue of $1 - \frac{0.01}{2} = 0.995$ , so $Z = 2.575$ .

(a) he uses a previous estimate of 25%?

we need a sample of size at least n.

n is found when $M = 0.02, \pi = 0.25$ . So

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.02 = 2.575\sqrt{\frac{0.25*0.75}{n}}$

$0.02\sqrt{n} = 2.575\sqrt{0.25*0.75}$

$\sqrt{n} = \frac{2.575\sqrt{0.25*0.75}}{0.02}$

$(\sqrt{n})^{2} = (\frac{2.575\sqrt{0.25*0.75}}{0.02})^{2}$

$n = 3108.1$

We need a sample size of at least 3109.

(b) he does not use any prior estimates?

When we do not use any prior estimate, we use $\pi = 0.5$

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.02 = 2.575\sqrt{\frac{0.5*0.5}{n}}$

$0.02\sqrt{n} = 2.575\sqrt{0.5*0.5}$

$\sqrt{n} = \frac{2.575\sqrt{0.5*0.5}}{0.02}$

$(\sqrt{n})^{2} = (\frac{2.575\sqrt{0.5*0.5}}{0.02})^{2}$

$n = 4144.1$

Rounding up

We need a sample size of at least 4145.

8 0

3 years ago

Below is a Venn Diagram.

PIT_PIT [208]

Answer:

A = 8, B = 9 and C = 6.

Step-by-step explanation:

We can create equations to solve this:

6 + A = 14

So A = 8.

A + B = 17

8 + B = 17

B = 9.

C = 29 - (6 + A + B)

= 29 - ( 6 + 8 + 9)

= 29 - 23

= 6.

6 0

3 years ago

Solve the system of equations below

DENIUS [597]

Answer:

The answer is B. (-7,-2)

Step-by-step explanation:

Multiply the first equation by 7,and multiply the second equation by -6.

7(−3x+6y=9)

−6(5x+7y=−49)

Becomes:

−21x+42y=63

−30x−42y=294

Add these equations to eliminate y:

−51x=357

Then solve−51x=357for x:

−51x=357 Divide both sides by -51

x=-7

Write down an original equation:

−3x+6y=9

Substitute−7forxin−3x+6y=9:

(−3)(−7)+6y=9

6y+21=9(Simplify both sides of the equation)

6y+21+−21=9+−21(Add -21 to both sides)

6y=−12

y=-2

4 0

3 years ago

Pollsters are concerned about declining levels of cooperation among persons contacted in surveys. A pollster contacts 95 people

Marrrta [24]

Answer:

Step-by-step explanation:

here you go

8 0

2 years ago

Find the slope and the y-intercept of the graph of the linear equation. y=-7x+12<br><br>

Sever21 [200]

Slope = -7

Y intercept= 13

7 0

1 year ago

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