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Mazyrski [523]
3 years ago
15

A humanities professor assigns letter grades on a test according to the following scheme. A: Top 12% of scores B: Scores below t

he top 12% and above the bottom 61% C: Scores below the top 39% and above the bottom 21% D: Scores below the top 79% and above the bottom 6% F: Bottom 6% of scores Scores on the test are normally distributed with a mean of 67.7 and a standard deviation of 7.8. Find the minimum score required for an A grade. Round your answer to the nearest whole number, if necessary.
Mathematics
1 answer:
allsm [11]3 years ago
3 0

Answer:

The minimum score required for an A grade is 77.

Step-by-step explanation:

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.

In this question, we have that:

\mu = 67.7, \sigma = 7.8

Find the minimum score required for an A grade.

Top 12% of scores get an A.

100-12 = 88th percentile.

The 88th percentile of scores is the minimum required for an A grade. This score is X when Z has a pvalue of 0.88. So X when Z = 1.175.

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

1.175 = \frac{X - 67.7}{7.8}

X - 67.7 = 7.8*1.175

X = 76.865

Rounding to the nearest whole number:

The minimum score required for an A grade is 77.

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Can somebody explain how trigonometric form polar equations are divided/multiplied?
koban [17]

Answer:

Attachment 1 : Option C

Attachment 2 : Option A

Step-by-step explanation:

( 1 ) Expressing the product of z1 and z2 would be as follows,

14\left[\cos \left(\frac{\pi \:}{5}\right)+i\sin \left(\frac{\pi \:\:}{5}\right)\right]\cdot \:2\sqrt{2}\left[\cos \left(\frac{3\pi \:}{2}\right)+i\sin \left(\frac{3\pi \:\:}{2}\right)\right]

Now to solve such problems, you will need to know what cos(π / 5) is, sin(π / 5) etc. If you don't know their exact value, I would recommend you use a calculator,

cos(π / 5) = \frac{\sqrt{5}+1}{4},

sin(π / 5) = \frac{\sqrt{2}\sqrt{5-\sqrt{5}}}{4}

cos(3π / 2) = 0,

sin(3π / 2) = - 1

Let's substitute those values in our expression,

14\left[\frac{\sqrt{5}+1}{4}+i\frac{\sqrt{2}\sqrt{5-\sqrt{5}}}{4}\right]\cdot \:2\sqrt{2}\left[0-i\right]

And now simplify the expression,

14\sqrt{5-\sqrt{5}}+i\left(-7\sqrt{10}-7\sqrt{2}\right)

The exact value of 14\sqrt{5-\sqrt{5}} = 23.27510\dots and (-7\sqrt{10}-7\sqrt{2}\right)) = -32.03543\dots Therefore we have the expression 23.27510 - 32.03543i, which is close to option c. As you can see they approximated the solution.

( 2 ) Here we will apply the following trivial identities,

cos(π / 3) = \frac{1}{2},

sin(π / 3) = \frac{\sqrt{3}}{2},

cos(- π / 6) = \frac{\sqrt{3}}{2},

sin(- π / 6) = -\frac{1}{2}

Substitute into the following expression, representing the quotient of the given values of z1 and z2,

15\left[cos\left(\frac{\pi \:}{3}\right)+isin\left(\frac{\pi \:\:}{3}\right)\right] \div \:3\sqrt{2}\left[cos\left(\frac{-\pi \:}{6}\right)+isin\left(\frac{-\pi \:\:}{6}\right)\right] ⇒

15\left[\frac{1}{2}+\frac{\sqrt{3}}{2}\right]\div  \:3\sqrt{2}\left[\frac{\sqrt{3}}{2}+-\frac{1}{2}\right]

The simplified expression will be the following,

i\frac{5\sqrt{2}}{2} or in other words \frac{5\sqrt{2}}{2}i or \frac{5i\sqrt{2}}{2}

The solution will be option a, as you can see.

6 0
4 years ago
14=-(p-8) <br> how do i find p
Xelga [282]

Answer:

p=-6

Step-by-step explanation:

14 = -(p-8)   (distribute negative into parentheses)

14 = p(-1) -8(-1)

14 = -p + 8   (subtract 8 from both sides)

14 - 8 = -p

6 = -p   (multiply both sides by -1 and rearrange)

p = 6(-1) = -6

3 0
3 years ago
The lines below are parallel. If the green line has a slope of -1, what is the slope of the red line? Enter your answer as an in
ololo11 [35]

Answer:

The red line has a slope of -1

Step-by-step explanation:

This is because parallel lines have the same slope with a different y intercept.

If the green line's slope is -1 and it is parallel to the redline, they will have the same slope.

5 0
3 years ago
X + 2y = 6<br> (3x + 8y = 4
prohojiy [21]

Answer:

Both of them would just stay how they are

Step-by-step explanation:

Unless the x and y have a value that you have shown it would just stay at the same standard so there is not answer also no answer would be added.

3 0
3 years ago
Here is a right-angled triangle.
stiv31 [10]

Answer:

Hypotenuse = 10 Cm

Step-by-step explanation:

Given:

θ = 60°

Base = 5 cm

Hypotenuse = x cm

Find:

Hypotenuse

Computation:

Cos θ = Base / Hypotenuse

Cos 60° = 5 / Hypotenuse

0.5 = 5 / Hypotenuse

Hypotenuse = 10 Cm

7 0
3 years ago
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