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irina1246 [14]
3 years ago
6

PLease help!!!!!!!!!!!!!!!!!!!!!!1

Mathematics
2 answers:
Andrew [12]3 years ago
5 0
4(5x-20)=-20
20x-80=-20 ======> Add 80 to both sides
20x-80+80=-20+80
20x=60======> Divide both sides by 20
20/20x=60/20
x=3
schepotkina [342]3 years ago
3 0
4(5x-20)= -20

20x-80= -20
      +80  +80
____________

20x=60
_______
      20

x=3
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Miles is saving to buy a new car. He currently has $600 in his savings account. He plans on depositing $200 a month until he has
Marizza181 [45]

Answer:

7 months

Step-by-step explanation:

He plans on depositing $200 every month into the savings account that already has $600 in it.

We can represent the amount of money he will have after a certain number of months (x) as:

A = 600 + 200x

He needs to save $2000. Therefore, to find the months he needs to save, we need to find x when A is $2000:

2000 = 600 + 200x

200x = 2000 - 600

200x = 1400

x = 1400/200 = 7 months

He needs to save for 7 months.

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3 years ago
The average Act score follows a normal distribution, with a mean of 21.1 and a standard deviation of 5.1. What is the probabilit
ohaa [14]

Answer:

0.43% probability that the mean IQ score of 50 randomly selected people will be more than 23

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 normally distributed samples are solved using 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:

\mu = 21.1, \sigma = 5.1, n = 50, s = \frac{5.1}{\sqrt{50}} = 0.7212

What is the probability that the mean IQ score of 50 randomly selected people will be more than 23

This is 1 subtracted by the pvalue of Z when X = 23. So

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

By the Central Limit Theorem

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

Z = \frac{23 - 21.1}{0.7212}

Z = 2.63

Z = 2.63 has a pvalue of 0.9957

1 - 0.9957 = 0.0043

0.43% probability that the mean IQ score of 50 randomly selected people will be more than 23

5 0
3 years ago
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AleksAgata [21]
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What is the answer to 227-198?
andreev551 [17]

Answer:

this answer is 29.....

5 0
2 years ago
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