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morpeh [17]
3 years ago
9

Three times a certain number, n, is 21​

Mathematics
1 answer:
Phantasy [73]3 years ago
7 0

Answer: 7

Step-by-step explanation:

3n=21

n=7

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A coin contains 9 grams of nickel and 16 grams of copper,for a total weight of 25 grams what percentage of the metal in the coin
Yanka [14]
16/25=64%.........
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5 0
2 years ago
Please help me with this. I will appreciate all the help ^^
Usimov [2.4K]

Answer:

80 minutes (first one)

Step-by-step explanation:

1/6 of an hour=10 min

3 ppl can go on the ride at the same time

so 24/3=8

leaving 8 more turns before emma's turn

8x10=10

3 0
2 years ago
What are the zeros of the graphed function y = (x + 3)(x + 5)? –5 and –3 5 and 3 –8 and 5 0 and 5
Sati [7]

Answer:

Answers are:  (x+3)(x+5) = 0

So first zero:  x+3 = 0  so x = -3

Second zero: x+5 = 0 so x = -5

so zeros are: x = -5 and -3

Step-by-step explanation:

6 0
3 years ago
Read 2 more answers
The amount people pay for cable service varies quite a bit but the mean monthly fee is $142 and the standard deviation is $29. t
zhuklara [117]

Answer:

a) By the Central Limit Theorem, the mean is $142 and the standard deviation is $0.7488.

b) By the Central Limit Theorem, approximately normal.

c) 0.0901 = 9.01% probability that the average cable service paid by the sample of cable service customers will exceed $143

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.

The mean monthly fee is $142 and the standard deviation is $29.

This means that \mu = 142, \sigma = 29

Part a: what are the mean an standard deviation of the sample distribution of x hat show your work and justify your reasoning.

Sample of 1500(larger than 30).

By the Central Limit Theorem

The mean is $142

The standard deviation is s = \frac{29}{\sqrt{1500}} = 0.7488

Part b: what is the shape of the sampling distribution of x hat justify your answer.

By the Central Limit Theorem, approximately normal.

Part C: what is the probability that the average cable service paid by the sample of cable service customers will exceed $143?

This is 1 subtracted by the pvalue of Z when X = 143. So

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

By the Central Limit Theorem

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

Z = \frac{143 - 142}{0.7488}

Z = 1.34

Z = 1.34 has a pvalue of 0.9099

1 - 0.9099 = 0.0901

0.0901 = 9.01% probability that the average cable service paid by the sample of cable service customers will exceed $143

4 0
3 years ago
The number of stamps that kaye and alberto had were in the ratio 5 : 3, respectively. after kaye gave alberto 10 of her stamps,
Gala2k [10]
K:A
5:3 (before)
15:9

since the total number of stamps didn't change, the total ratio should be the same.

7:5(after)
14:10

so this means 1 unit is 10stamps.

14-10=4
4 X 10= 40

Kaye have 40 more stamps than Alberto.
4 0
2 years ago
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