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marta [7]
2 years ago
11

PLEASE HELP WILL GIVE BRAINLIEST the number of students at north middle school is 1240 and is decreasing by 25 students per year

. The number of students at south middle school is 800 and it is decreasing by 30 students per year. in how many years will the two schools have the same number of students?
Mathematics
1 answer:
Nikolay [14]2 years ago
6 0

Answer:

-88

Step-by-step explanation:

Let N(x) be the number of students at NMS for a certain number of years.

Let S(x) be the number of students at SMS for a certain number of years.

Let x be the number of years.

N(x)=1240-25x

S(x)=800-30x

When # of students is equal, N(x)=S(x). Therefore, we are looking for the value of x (# of years) when 1240-25x=800-30x

Subtract 1240 from each side

-25x=-440-30x

Add 30x

5x=-400

x=-88 years

Check your numbers.

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Step-by-step explanation:

(3 degrees Celsius - 5 degrees Celsius)= -2 degrees Celsius

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A first number plus twice a second number is 9. Twice the first number plus the second totals 27. Find the numbers
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System of equations <br><br> -8x + 4y = 24<br> -7x + 7y = 28<br><br> X= ___<br> Y=___
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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
Tara is the editor of the school newspaper. She tries to devote about 1/2 of the paper to news, 1/3 to pictures, and the remaind
Klio2033 [76]
5/6 of the paper is devoted to news and pictures

first I made the fraction have equal denominators which was 6 by doing that I multiplyed the numerator and the denominator

1/2
1×3=3
2×3=6
therefore 1/2 being equivalent to 3/6


1/3
1×2=2
3×2=6
therefore 1/3 being equivalent to 2/6

now you would be able to add the numerators, so 2+3=5
therefore being 5/6 of the paper is devoted to news and pictures
4 0
3 years ago
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