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marishachu [46]
2 years ago
10

NEEED HELPPPP TRYING NOT TO FAIL MATHH !!

Mathematics
1 answer:
Oliga [24]2 years ago
3 0
The answer is C hope it helped
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A researcher reports survey results by stating that the standard error of the mean is 25 the population standard deviation is 40
bezimeni [28]

Answer:

a) A sample of 256 was used in this survey.

b) 45.14% probability that the point estimate was within ±15 of the population mean

Step-by-step explanation:

This question is solved using the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use 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}

The Z-score measures how many standard deviations the measure is from the mean. 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, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean \mu and standard deviation \sigma, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}.

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

a. How large was the sample used in this survey?

We have that s = 25, \sigma = 400. We want to find n, so:

s = \frac{\sigma}{\sqrt{n}}

25 = \frac{400}{\sqrt{n}}

25\sqrt{n} = 400

\sqrt{n} = \frac{400}{25}

\sqrt{n} = 16

(\sqrt{n})^2 = 16^2[tex][tex]n = 256

A sample of 256 was used in this survey.

b. What is the probability that the point estimate was within ±15 of the population mean?

15 is the bounds with want, 25 is the standard error. So

Z = 15/25 = 0.6 has a pvalue of 0.7257

Z = -15/25 = -0.6 has a pvalue of 0.2743

0.7257 - 0.2743 = 0.4514

45.14% probability that the point estimate was within ±15 of the population mean

3 0
3 years ago
A boy is Y years old. His father is twice as old as he is. The sum of their ages is 63. How old is the boy?
Arturiano [62]
Hi!
Divide 63 by 3. You will get 21. That is the boys age. His father’s age is 42. When combined their age is 63.
3 0
2 years ago
Read 2 more answers
The surface area and volume of a sphere are in the ratio of 3:7cm.What is the circumference of its great circle and volume​
marishachu [46]

Answer:

Radius of sphere =1unit

SurfaceareaVolume=4πr234πr3=34π(1)3×4π(1)21=31

∴V:S=1:3 cm

Step-by-step explanation:

Hope this helps. If any questions, please ask in comments.

3 0
2 years ago
On the number line above, points J, K, L, and M are integers, and JK:KL:KM = 2:1:3. What is the value of KM? number line shown b
Rama09 [41]

Answer:

<h2>F. 12</h2>

Step-by-step explanation:

The distance between A and M i.e JM = M - J = 5-(-19)

JM = 5+19

JM = 24

If JK:KL:KM = 2:1:3

The total ratio = 2+1+3

Total ratio = 6

Dividing each length based on ratio

length JK = 2/6 * JM

JK = 1/3 * 24

JK = 8

length KL = 1/6 * JM

KL = 1/6 * 24

KL = 4

length KM = 3/6 * JM

KM = 1/2 * 24

KM = 12

<em>Hence the value of KM is 12</em>

3 0
3 years ago
-9-2+4 = 90<br> (Absolute value)
elena-14-01-66 [18.8K]

Answer:

[90]

Step-by-step explanation:

3 0
3 years ago
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