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mote1985 [20]
4 years ago
12

Aliyah had $24 to spend on seven pencils. after buying them she had $10. how much did each pencil cost?​

Mathematics
2 answers:
aliya0001 [1]4 years ago
6 0

Answer:

2

Step-by-step explanation:

Firlakuza [10]4 years ago
4 0

Answer:

I'm pretty sure the answer would be 2 but correct me if I'm wrong

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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

So

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
4 years ago
A student wanted to find the sum of all the even numbers from 1 to 100. He said:
murzikaleks [220]

Answer:

The statements are incorrect as: The sum of even numbers from 1 to 100(i.e. 2550) is not double\twice of the sum of odd numbers from 1 to 100(i.e. 2500).

Step-by-step explanation:

We know that sum of an Arithmetic Progression(A.P.) is given by:

where 'n' denotes the "number" of digits whose sum is to be determined, 'a' denotes the first digit of the series and '' denote last digit of the series.

Now the sum of even numbers i.e. 2+4+6+8+....+100 is given by the use of sum of the arithmetic progression since the series is an A.P. with a common difference of 2.

image with explanation

Hence, sum of even numbers from 1 to 100 is 2550.

Also the series of odd numbers is an A.P. with a common difference of 2.

sum of odd numbers from 1 to 100 is given by: 1+3+5+....+99

.

Hence, the sum of all the odd numbers from 1 to 100 is 2500.

Clearly the sum of even numbers from 1 to 100(i.e. 2550) is not double of the sum of odd numbers from 1 to 100(i.e. 2500).

Hence the statement is incorrect.

Step-by-step explanation:

3 0
3 years ago
PLEASE HELP ASAP!!!!!Test Grade!!!!!!!!<br>please incude step by step explination
Mariulka [41]
The answer is D. 10. Let me know if you want me to show my work
4 0
3 years ago
Read 2 more answers
-6=-8+<br><img src="https://tex.z-dn.net/?f=%20%5Cfrac%7Bp%7D%7B11%7D%20" id="TexFormula1" title=" \frac{p}{11} " alt=" \frac{p}
vekshin1
P=22 rewrite the question as -8+p/11=-6 then move all terms not containing p to the right side p/11=2 multiply both sides of the given equation by 11, the reciprocal, 11*p/11=11*2
8 0
3 years ago
Sean tossed a coin off a bridge into the stream below. The path of the coin can be represented by the equation 2 h tt = − 16t^2+
tekilochka [14]

Answer:

It will take 5.61 seconds for the coin to reach the stream.

Step-by-step explanation:

The height of the coin, after t seconds, is given by the following equation:

h(t) = -16t^{2} + 72t + 100

How long will it take the coin to reach the stream?

The stream is the ground level.

So the coin reaches the stream when h(t) = 0.

h(t) = -16t^{2} + 72t + 100

-16t^{2} + 72t + 100 = 0

Multiplying by (-1)

16t^{2} - 72t - 100 = 0

Solving a quadratic equation:

Given a second order polynomial expressed by the following equation:

ax^{2} + bx + c, a\neq0.

This polynomial has roots x_{1}, x_{2} such that ax^{2} + bx + c = a(x - x_{1})*(x - x_{2}), given by the following formulas:

x_{1} = \frac{-b + \sqrt{\bigtriangleup}}{2*a}

x_{2} = \frac{-b - \sqrt{\bigtriangleup}}{2*a}

\bigtriangleup = b^{2} - 4ac

In this question:

16t^{2} - 72t - 100 = 0

So

a = 16, b = -72, c = -100

\bigtriangleup = (-72)^{2} - 4*16*(-100) = 11584

t_{1} = \frac{-(-72) + \sqrt{11584}}{2*16} = 5.61

t_{2} = \frac{-(-72) - \sqrt{11584}}{2*16} = -1.11

Time is a positive measure, so we take the positive value.

It will take 5.61 seconds for the coin to reach the stream.

3 0
4 years ago
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