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3241004551 [841]
2 years ago
14

How do I slow this problem

Mathematics
1 answer:
bija089 [108]2 years ago
7 0

Answer:

D.)  4

Step-by-step explanation:

Here,

1.25(4x-10)=7.5

5x-12.5=7.5

5x=7.5+12.5

x=20/5

x=4

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A number is decreased by 40% to 525. what is the original amount?​
zhenek [66]

Answer:

875

Step-by-step explanation:

lets assume the original amount X

the new amount = X - ( X × 40% )

525 = (60 × X) ÷ 100

X = ( 525 × 100 ) ÷ 60

<u>X = 875</u>

6 0
2 years ago
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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
What value of "a" makes the system 3x-y=17 and ax+y=-7 have no solution?
Norma-Jean [14]

Answer:

y=-7-ax

3x-(-7-ax)=17

3x+7+ax=17

3x+ax=10

x(3+a)=10

x=10,3+a=10 a=10-3 a=7

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3 years ago
What is 1/10 of 0.06
Vesna [10]

Answer:

0.006

Step-by-step explanation:

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2 years ago
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Answer:

A

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