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2 years ago

Can someone help. I’m having trouble with the equation part

Mathematics

1 answer:

mote1985 [20]2 years ago

7 0

Answer:

(x+3) x+7 is the answer for the first question if it's the same way my school does it. Whatever you put in parentheses is the opposite of what you think. + is going to the left. - is going to the right but those only apply when in parentheses.

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Find the value of x, and please explain how you got x

katen-ka-za [31]

X equals to 48

The work is shown in the picture. I hope this helps.

8 0

2 years ago

Power +, Inc. produces AA batteries used in remote-controlled toy cars. The mean life of these batteries follows the normal prob

Novay_Z [31]

Answer:

a) By the Central Limit Theorem, it is approximately normal.

b) The standard error of the distribution of the sample mean is 1.8333.

c) 0.1379 = 13.79% of the samples will have a mean useful life of more than 38 hours.

d) 0.7939 = 79.39% of the samples will have a mean useful life greater than 34.5 hours

e) 0.656 = 65.6% of the samples will have a mean useful life between 34.5 and 38 hours

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score 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 p-value, 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.

Mean of 36 hours and a standard deviation of 5.5 hours.

This means that $\mu = 36, \sigma = 5.5$

a. What can you say about the shape of the distribution of the sample mean?

By the Central Limit Theorem, it is approximately normal.

b. What is the standard error of the distribution of the sample mean? (Round your answer to 4 decimal places.)

Sample of 9 means that $n = 9$ . So

$s = \frac{\sigma}{\sqrt{n}} = \frac{5.5}{\sqrt{9}} = 1.8333$

The standard error of the distribution of the sample mean is 1.8333.

c. What proportion of the samples will have a mean useful life of more than 38 hours?

This is 1 subtracted by the pvalue of Z when X = 38. So

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

By the Central Limit Theorem

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

$Z = \frac{38 - 36}{1.8333}$

$Z = 1.09$

$Z = 1.09$ has a pvalue of 0.8621

1 - 0.8621 = 0.1379

0.1379 = 13.79% of the samples will have a mean useful life of more than 38 hours.

d. What proportion of the sample will have a mean useful life greater than 34.5 hours?

This is 1 subtracted by the pvalue of Z when X = 34.5. So

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

$Z = \frac{34.5 - 36}{1.8333}$

$Z = -0.82$

$Z = -0.82$ has a pvalue of 0.2061.

1 - 0.2061 = 0.7939

0.7939 = 79.39% of the samples will have a mean useful life greater than 34.5 hours.

e. What proportion of the sample will have a mean useful life between 34.5 and 38 hours?

pvalue of Z when X = 38 subtracted by the pvalue of Z when X = 34.5. So

0.8621 - 0.2061 = 0.656

0.656 = 65.6% of the samples will have a mean useful life between 34.5 and 38 hours

4 0

2 years ago

A property sells for $620,000 two years after it was purchased. If the annual appreciation rate was 4%, how much did the origina

8090 [49]

$25,000 is the answer you would take $620,000 x 0.04 (4%)= 24,800 which rounds to 25,000

6 0

2 years ago

Read 2 more answers

For a set of five whole numbers, the mean is 4, the mode is 1, and the median is 5. What are the five numbers?

zmey [24]

SO we need 5 numbers that equal to 20, with 5 being the middle number, and ones being the most used number so

1 1 5 x y

According to this, x and y must equal 13 and both be bigger then 5. Because we can rule out every other number, x and y must be 6 and 7.

Your 5 numbers are 1, 1, 5, 6, 7.

5 0

2 years ago

A bottle of hot sauce is 3/4 full. Leigh uses 2/9 of the contents of the hot sauce bottle for lunch. How much of a full bottle o

Alexxx [7]

Answer:

C) 1/6

Step-by-step explanation:

2/9 of 3/4 is ...

$\dfrac{2}{9}\times\dfrac{3}{4}=\dfrac{2\cdot 3}{9\cdot 4}=\dfrac{6}{36}=\boxed{\dfrac{1}{6}}\qquad\text{matches C}$

5 0

2 years ago