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spayn [35]
3 years ago
7

Assume that the heights of men are normally distributed with a mean of 69.0 inches and a standard deviation of 2.8 inches. If th

e top 5 percent and bottom 15 percent are excluded for an experiment, what is the bottom cutoff heights to be eligible for this experiment? Round your answers to one decimal place.
Mathematics
1 answer:
ioda3 years ago
8 0

Answer:

The bottom cutoff heights to be eligible for this experiment is 66.1 inches.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be 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.

Mean of 69.0 inches and a standard deviation of 2.8 inches.

This means that \mu = 69, \sigma = 2.8

What is the bottom cutoff heights to be eligible for this experiment?

The bottom 15% are excluded, so the bottom cutoff is the 15th percentile, which is X when Z has a pvalue of 0.15. So X when Z = -1.037.

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

-1.037 = \frac{X - 69}{2.8}

X - 69 = -1.037*2.8

X = 66.1

The bottom cutoff heights to be eligible for this experiment is 66.1 inches.

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Ben and Josh went to the roof of their 40-foot tall high school to throw their math books offthe edge.The initial velocity of Be
Taya2010 [7]

Answer

Josh's textbook reached the ground first

Josh's textbook reached the ground first by a difference of t=0.6482

Step-by-step explanation:

Before we proceed let us re write correctly the height equation which in correct form reads:

h(t)=-16t^2 +v_{o}t+s       Eqn(1).

Where:

h(t) : is the height range as a function of time

v_{o}   : is the initial velocity

s     : is the initial heightin feet and is given as 40 feet, thus Eqn(1). becomes:

h(t)=-16t^2 + v_{o}t + 40        Eqn(2).

Now let us use the given information and set up our equations for Ben and Josh.

<u>Ben:</u>

We know that v_{o}=60ft/s

Thus Eqn. (2) becomes:

h(t)=-16t^2+60t+40        Eqn.(3)

<u>Josh:</u>

We know that v_{o}=48ft/s

Thus Eqn. (2) becomes:

h(t)=-16t^2+48t+40       Eqn. (4).

<em><u>Now since we want to find whose textbook reaches the ground first and by how many seconds we need to solve each equation (i.e. Eqns. (3) and (4)) at </u></em>h(t)=0<em><u>. Now since both are quadratic equations we will solve one showing the full method which can be repeated for the other one. </u></em>

Thus we have for Ben, Eqn. (3) gives:

h(t)=0-16t^2+60t+40=0

Using the quadratic expression to find the roots of the quadratic we have:

t_{1,2}=\frac{-b+/-\sqrt{b^2-4ac} }{2a} \\t_{1,2}=\frac{-60+/-\sqrt{60^2-4(-16)(40)} }{2(-16)} \\t_{1,2}=\frac{-60+/-\sqrt{6160} }{-32} \\t_{1,2}=\frac{15+/-\sqrt{385} }{8}\\\\t_{1}=4.3276 sec\\t_{2}=-0.5776 sec

Since time can only be positive we reject the t_{2} solution and we keep that Ben's book took t=4.3276 seconds to reach the ground.

Similarly solving for Josh we obtain

t_{1}=3.6794sec\\t_{2}=-0.6794sec

Thus again we reject the negative and keep the positive solution, so Josh's book took t=3.6794 seconds to reach the ground.

Then we can find the difference between Ben and Josh times as

t_{Ben}-t_{Josh}= 4.3276 - 3.6794 = 0.6482

So to answer the original question:

<em>Whose textbook reaches the ground first and by how many seconds?</em>

  • Josh's textbook reached the ground first
  • Josh's textbook reached the ground first by a difference of t=0.6482

3 0
3 years ago
The table shows how much money Edguardo earns as a golf coach. He charges a flat fee of $38, plus $22 per hour. Complete the tab
Vesnalui [34]
Let's re-read the statement and question, and then break it down.
He charges a flat fee of $38, plus $22 per hour.
A flat fee of $38 is only a one-time pay, and will never be paid for again.
This means if after two hours, we only add $38 once overall, never more.
Every hour that goes by, he earns $22 each hour.
Now that we've broken this down, we can make an equation.
Let's do 1 hour.
1(22) + 38 = 22 + 38, = 60.
For 1 hour he earns $60.
Let's do 2 hours.
2(22) + 38 = 44 + 38, = 82.
For 2 hours he earns $82.
Let's do 3 hours.
3(22) + 38 = 66 + 38, = 104.
For 3 hours he earns $104.
Let's do 4 hours.
4(22) + 38 = 88 + 38, = 126.
For 4 hours he earns $126.
This is a pattern.
Now let's do 8 hours, which is the main question, "How much does he make in 8 hours?".
8(22) + 38 = 176 + 38, = 214.
For 8 hours he earns $214.
I hope this helps!
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Part b.) d = 7

Part C The diagonals are each 8

Step-by-step explanation: part b:

35= 10d/2 70= 10d. 7 =d

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√64 = √c²

c = 8

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The center of a circle is the point from which the circumference is equidistant

Step-by-step explanation:

Radius of a circle is a line drawn from the center of the circle to the circumference.

4 0
3 years ago
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31.5
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