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2 years ago

Peggy had 4 times as many quarters as nickels. She had $2.10 in all. How many nickes and how many qurters did she have ?

1 answer:

8 0

A) 4*N -Q = 0
B) .05N + .25Q = 2.10

Multiply B) by 4
B) .2N + Q = 8.40 Adding this to A)
A) 4*N -Q = 0
4.2N = 8.40
N = 2 Nickels
Q = 8 Quarters

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We would like to create a confidence interval.

Vlada [557]

Answer:

c.A 90% confidence level and a sample size of 300 subjects.

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 $1-\alpha$ , we have the confidence interval with a margin of error of:

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

In which

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

In this problem

The proportions are the same for all the options, so we are going to write our margins of error as functions of $\sqrt{\pi(1-\pi)}$

a.A 99% confidence level and a sample size of 50 subjects.

$n = 50$

99% confidence interval

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

The margin of error is

$M = z\sqrt{\frac{\pi(1-\pi)}{n}} = \frac{2.575}{\sqrt{50}}\sqrt{\pi(1-\pi)} = 0.3642\sqrt{\pi(1-\pi)}$

b.A 90% confidence level and a sample size of 50 subjects.

$n = 50$

90% confidence interval

So $\alpha = 0.1$ , z is the value of Z that has a pvalue of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

The margin of error is

$M = z\sqrt{\frac{\pi(1-\pi)}{n}} = \frac{1.645}{\sqrt{50}}\sqrt{\pi(1-\pi)} = 0.2623\sqrt{\pi(1-\pi)}$

c.A 90% confidence level and a sample size of 300 subjects.

$n = 300$

90% confidence interval

So $\alpha = 0.1$ , z is the value of Z that has a pvalue of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

The margin of error is

$M = z\sqrt{\frac{\pi(1-\pi)}{n}} = \frac{1.645}{\sqrt{300}}\sqrt{\pi(1-\pi)} = 0.0950\sqrt{\pi(1-\pi)}$

This produces smallest margin of error.

d.A 99% confidence level and a sample size of 300 subjects.

$n = 300$

99% confidence interval

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

The margin of error is

$M = z\sqrt{\frac{\pi(1-\pi)}{n}} = \frac{2.575}{\sqrt{300}}\sqrt{\pi(1-\pi)} = 0.1487\sqrt{\pi(1-\pi)}$

6 0

3 years ago

PLEASE HELP ANSWER BOTH PARTS!!! DUE SOON

soldi70 [24.7K]

Answer:

c. 69

b. 7

Step-by-step explanation:

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1 year ago

Classify this by degree and by number of terms?

sveta [45]

The answer is quintic binomial.

It is quintic because its highest power is 5. Quartic would mean its highest power is 4.

It is a binomial because the two terms are -4x^5 and -6x^3. Terms are separated by + or - signs.

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3 years ago

Help it’s confusing

noname [10]

Answer:

I think is C like I said not quite sure...

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2 years ago

Read 2 more answers

The circumference of a roll of party streamers is 9 inches. The circumference decreases by 2 inches after you use the streamers

leonid [27]

For that case the new circumference is:
C = 9 - 2
C = 7 inches
By definition, the circumference is:
C = 2 * pi * r
Where,
r: radio
Substituting values:
7 = 2 * pi * r
Clearing the radio:
r = 7 / (2 * pi)
Then, the diameter is:
d = 2 * r
Substituting:
d = 2 * (7 / (2 * pi))
d = 2.228169203
Round to the hundredth:
d = 2.23 inches
Answer:
The diameter of the roll after the decrease is:
d = 2.23 inches

7 0

2 years ago