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MatroZZZ [7]
3 years ago
12

Your current test average in Science is an 81. You’ve taken 5 tests. You only have one test remaining (there is not extra credit

on your test). You can raise your average to an 85.
Mathematics
2 answers:
stepladder [879]3 years ago
8 0
If you want to know what grade is needed to raise your average to an 85, add all tests, then divide by total number of tests to equal average of 85. The x value is the grade needed on the final to raise the overall class grade to an 85.

x= final test


(81 + 81 + 81 + 81 + 81 + x)/6= 85
add in parentheses

(405 + x)/6= 85
multiply both sides by 6

405 + x= 510
subtract 405 from both sides

x= 105 grade needed


ANSWER: Since there is no extra credit, it is impossible to raise the overall average to an 85 because they would need a final test grade of 105.

Hope this helps! :)
Leto [7]3 years ago
5 0
What exactly are you asking?
You might be interested in
A population has a mean of 200 and a standard deviation of 50. Suppose a sample of size 100 is selected and x is used to estimat
zmey [24]

Answer:

a) 0.6426 = 64.26% probability that the sample mean will be within +/- 5 of the population mean.

b) 0.9544 = 95.44% probability that the sample mean will be within +/- 10 of the population mean.

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.

In this question, we have that:

\mu = 200, \sigma = 50, n = 100, s = \frac{50}{\sqrt{100}} = 5

a. What is the probability that the sample mean will be within +/- 5 of the population mean (to 4 decimals)?

This is the pvalue of Z when X = 200 + 5 = 205 subtracted by the pvalue of Z when X = 200 - 5 = 195.

Due to the Central Limit Theorem, Z is:

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

X = 205

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

Z = \frac{205 - 200}{5}

Z = 1

Z = 1 has a pvalue of 0.8413.

X = 195

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

Z = \frac{195 - 200}{5}

Z = -1

Z = -1 has a pvalue of 0.1587.

0.8413 - 0.1587 = 0.6426

0.6426 = 64.26% probability that the sample mean will be within +/- 5 of the population mean.

b. What is the probability that the sample mean will be within +/- 10 of the population mean (to 4 decimals)?

This is the pvalue of Z when X = 210 subtracted by the pvalue of Z when X = 190.

X = 210

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

Z = \frac{210 - 200}{5}

Z = 2

Z = 2 has a pvalue of 0.9772.

X = 195

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

Z = \frac{190 - 200}{5}

Z = -2

Z = -2 has a pvalue of 0.0228.

0.9772 - 0.0228 = 0.9544

0.9544 = 95.44% probability that the sample mean will be within +/- 10 of the population mean.

7 0
3 years ago
Please answer this correctly
balu736 [363]

Answer:

2 years 5 months

Step-by-step explanation:

TO solve, convert everything to months

1 year has 12 months, so 5 years would have 60, because we multiply by 5.

Then we add the remaining 2 months, 60+2 =62

Then we can convert 2 years to 24 months. Then we add the remaining 9 months to get 24+9, 33

Then we subtract the 2, and get 62-33= 29, and we divide by 12 to convert to years and months. 29 divided by 12 is 2 and 5 months

so your answer is 2 years and 5 months

4 0
3 years ago
2. A bookshelf costs $300 normally. Today it is on sale for 20% off. Which expression or expressions could you use to find the s
DaniilM [7]

Answer/Step-by-step explanation:

$300 is the normal price the sale is 20% off

You would need to multiply them together because it then gives you how much it is off.

Then then you would subtract it.

That takes D and C off.

A , is adding and we arnt adding we are subtracting.

Therefore you answer is: B

5 0
2 years ago
Order from least to greatest ---- -2.15 17/7 2.7 -2.105
9966 [12]
In order from least to greatest ---- -2.15, -2.105, 17/7, 2.7 
6 0
3 years ago
The volume of the box is 60 cubic inches. What are<br> the length, width, and height of the box?
Serggg [28]

Answer: The volume is the product of the Length, Width, and Height: V = LWH.

Step-by-step explanation: We are given V = 240 in.3, and H = 6 in., and L = W + 3 in.

Thus 240 in.3 = (W+3 in.)*W*(6 in.) so W(W+3 in.) = 240 in.3 / 6 in. = 40 in.2

Using the distributive property and moving the constant to the left gives:

W2 + (3 in.)W - 40 in.2 = 0

This factors:

(W + 8 in.)(W - 5 in.) = 0

The first factor gives W = -8 in. which is nonsense because it is negative.

The second factor gives a valid answer of W = 5 in.

8 0
3 years ago
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