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Vitek1552 [10]
3 years ago
7

Anyone can help me with questions

Mathematics
1 answer:
Alex777 [14]3 years ago
4 0

Answer:

3x+18+4x+15=180

7x+33=180

7x=147

x=21

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Suppose the test scores for a college entrance exam are normally distributed with a mean of 450 and a s. d. of 100. a. What is t
svet-max [94.6K]

Answer:

a) 68.26% probability that a student scores between 350 and 550

b) A score of 638(or higher).

c) The 60th percentile of test scores is 475.3.

d) The middle 30% of the test scores is between 411.5 and 488.5.

Step-by-step explanation:

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.

In this problem, we have that:

\mu = 450, \sigma = 100

a. What is the probability that a student scores between 350 and 550?

This is the pvalue of Z when X = 550 subtracted by the pvalue of Z when X = 350. So

X = 550

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

Z = \frac{550 - 450}{100}

Z = 1

Z = 1 has a pvalue of 0.8413

X = 350

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

Z = \frac{350 - 450}{100}

Z = -1

Z = -1 has a pvalue of 0.1587

0.8413 - 0.1587 = 0.6826

68.26% probability that a student scores between 350 and 550

b. If the upper 3% scholarship, what score must a student receive to get a scholarship?

100 - 3 = 97th percentile, which is X when Z has a pvalue of 0.97. So it is X when Z = 1.88

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

1.88 = \frac{X - 450}{100}

X - 450 = 1.88*100

X = 638

A score of 638(or higher).

c. Find the 60th percentile of the test scores.

X when Z has a pvalue of 0.60. So it is X when Z = 0.253

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

0.253 = \frac{X - 450}{100}

X - 450 = 0.253*100

X = 475.3

The 60th percentile of test scores is 475.3.

d. Find the middle 30% of the test scores.

50 - (30/2) = 35th percentile

50 + (30/2) = 65th percentile.

35th percentile:

X when Z has a pvalue of 0.35. So X when Z = -0.385.

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

-0.385 = \frac{X - 450}{100}

X - 450 = -0.385*100

X = 411.5

65th percentile:

X when Z has a pvalue of 0.35. So X when Z = 0.385.

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

0.385 = \frac{X - 450}{100}

X - 450 = 0.385*100

X = 488.5

The middle 30% of the test scores is between 411.5 and 488.5.

7 0
3 years ago
Solve this please!!!!
Lilit [14]
Answer it’s 14

Explanation
Look at the middle letters from the three of them ( BNO) always pick the middle letter (N) like look at this

6 0
3 years ago
Morgan borrowed $0.35 from her mother every time she went to the gas station to buy some chips. Over the summer Morgan went to t
GarryVolchara [31]

Answer:

The money borrowed by Morgan is $ 3.15.

Step-by-step explanation:

Money borrowed by Morgan to buy chips = $ 0.35

Number of times goes to the station = 9

Money borrowed by Morgan in 9 time visit to station

= 9 x $ 0.35

=$ 3.15

5 0
2 years ago
Need help with this question
ElenaW [278]

Answer: its 432cm=m cubed

Step-by-step explanation:

im not telling you

3 0
3 years ago
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I will give brainleist again if you help me on this question and thanks for helping
algol [13]

Answer:

36 for area, 66 for surface area.

Step-by-step explanation:

I am not sure what it is asking, but if this is what you were asking for here it is. Surface area is harder to explain, but volume is multiply all dimensions.

Hope this is what it was asking!

5 0
3 years ago
Read 2 more answers
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