4(-3x – 5) = 2(-6x + 8)

A population has a mean of 200 and a standard deviation of 50. Suppose a sample of size 100 is selected and x is used to estimat

zmey [24]

Answer:

a) 0.6426 = 64.26% probability that the sample mean will be within +/- 5 of the population mean.

b) 0.9544 = 95.44% probability that the sample mean will be within +/- 10 of the population mean.

Step-by-step explanation:

To solve this question, we need to understand 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.

In this question, we have that:

$\mu = 200, \sigma = 50, n = 100, s = \frac{50}{\sqrt{100}} = 5$

a. What is the probability that the sample mean will be within +/- 5 of the population mean (to 4 decimals)?

This is the pvalue of Z when X = 200 + 5 = 205 subtracted by the pvalue of Z when X = 200 - 5 = 195.

Due to the Central Limit Theorem, Z is:

$Z = \frac{X - \mu}{s}$

X = 205

$Z = \frac{X - \mu}{s}$

$Z = \frac{205 - 200}{5}$

$Z = 1$

$Z = 1$ has a pvalue of 0.8413.

X = 195

$Z = \frac{X - \mu}{s}$

$Z = \frac{195 - 200}{5}$

$Z = -1$

$Z = -1$ has a pvalue of 0.1587.

0.8413 - 0.1587 = 0.6426

0.6426 = 64.26% probability that the sample mean will be within +/- 5 of the population mean.

b. What is the probability that the sample mean will be within +/- 10 of the population mean (to 4 decimals)?

This is the pvalue of Z when X = 210 subtracted by the pvalue of Z when X = 190.

X = 210

$Z = \frac{X - \mu}{s}$

$Z = \frac{210 - 200}{5}$

$Z = 2$

$Z = 2$ has a pvalue of 0.9772.

X = 195

$Z = \frac{X - \mu}{s}$

$Z = \frac{190 - 200}{5}$

$Z = -2$

$Z = -2$ has a pvalue of 0.0228.

0.9772 - 0.0228 = 0.9544

0.9544 = 95.44% probability that the sample mean will be within +/- 10 of the population mean.

7 0

3 years ago

the sum of four consecutive integers is 2174. what are the integers? (continuation) the smallest of four consecutive integers is

timofeeve [1]

The smallest of the four numbers is x.
Since the four numbers are consecutive, this means that each number is one more than the previous.
Therefore, the four numbers are:
x
x + 1
x+1 + 1 = x+2
x+2 + 1 = x+3

Now, we are given that the sum (s) of the four numbers is 2174
This means that:
s = x+x+1+x+2+x+3
s = 4x + 6

We are given that s = 2174. Substitute with s in the above equation and solve for x as follows:
2174 = 4x + 6
4x = 2174 - 6
4x = 2168
x = 2168 / 4
x = 542

Based on the above calculations, the four numbers are:
542, 543, 544 and 555

7 0

2 years ago

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Y=-2(x+5)^2-30 In standard form

Trava [24]

Answer:

y = -2 ( (x^2) + (2*x*5) + (5^2)) - 30

y = -2 ( x^2 + 10x + 25) - 30

y = -2x^2 - 20x - (2*25) - 30

y = -2x^2 - 20x - 50 - 30

y = -2x^2 - 20x - 80

3 0

3 years ago

A collar of Styrofoam is made to insulate a pipe. Find it's volume. That large R is to the outer rim. The smaller r us to the ed

anastassius [24]

Answer:

the volume of the pipe is 649.98 cubic inches.

Step-by-step explanation:

We have been given that a collar of Styrofoam is made to insulate a pipe. We are asked to find the volume of the given pipe.

We will use volume of hollow cylinder formula to solve our given problem.

$\text{Volume of hollow cylinder}=\pi R^2h-\pi r^2h$

where,

R = Radius of external cylinder,

r = Radius of internal cylinder.

h = Height of cylinder.

substituting our given values in above formula, we will get:

$\text{Volume of hollow cylinder}=\pi (5\text{ in})^2(\text{23 in})-\pi (4\text{ in})^2(\text{23 in})\text{Volume of hollow cylinder}=\text{23 in}\cdot 3.14 ((5\text{ in})^2-(4\text{ in})^2)\text{Volume of hollow cylinder}=\text{23 in}\cdot 3.14 (25\text{ in}^2-16\text{ in}^2)\text{Volume of hollow cylinder}=\text{23 in}\cdot 3.14 (9\text{ in}^2)\text{Volume of hollow cylinder}=649.98\text{ in}^3$

Therefore, the volume of the pipe is 649.98 cubic inches.

8 0

3 years ago

A spinner is divided into 8 equal sections: What is the theoretical probability of spinning and landing on 2, 7, or 5?

sp2606 [1]

3/8 because there are 3 numbers you want to land on and 8 total numbers.

6 0

3 years ago

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