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Diano4ka-milaya [45]
3 years ago
12

Use the normal approximation to the binomial distribution to answer this question. Fifteen percent of all students at a large un

iversity are absent on Mondays. If a random sample of 120 names is called on a Monday, what is the probability that less than twenty students are absent?
Mathematics
1 answer:
spayn [35]3 years ago
3 0

Answer:

60.26% probability that less than twenty students are absent

Step-by-step explanation:

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

E(X) = np

The standard deviation of the binomial distribution is:

\sqrt{V(X)} = \sqrt{np(1-p)}

Normal probability distribution

Problems of normally distributed samples 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.

When we are approximating a binomial distribution to a normal one, we have that \mu = E(X), \sigma = \sqrt{V(X)}.

In this problem, we have that:

n = 120, p = 0.15.

So

\mu = E(X) = np = 120*0.15 = 18

\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{120*0.15*0.85} = 3.91

If a random sample of 120 names is called on a Monday, what is the probability that less than twenty students are absent?

This is the pvalue of Z when X = 20-1 = 19. So

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

Z = \frac{19 - 18}{3.91}

Z = 0.26

Z = 0.26 has a pvalue of 0.6026.

60.26% probability that less than twenty students are absent

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slava [35]

Answer:

<h3><u>Question 7</u></h3>

<u>Lateral Surface Area</u>

The bases of a triangular prism are the triangles.

Therefore, the Lateral Surface Area (L.A.) is the total surface area excluding the areas of the triangles (bases).

\implies \sf L.A.=2(10 \times 6)+(3 \times 6)=138\:\:m^2

<u>Total Surface Area</u>

Area of the isosceles triangle:

\implies \sf A=\dfrac{1}{2}\times base \times height=\dfrac{1}{2}\cdot3 \cdot \sqrt{10^2-1.5^2}=\dfrac{3\sqrt{391}}{4}\:m^2

Total surface area:

\implies \sf T.A.=2\:bases+L.A.=2\left(\dfrac{3\sqrt{391}}{4}\right)+138=167.66\:\:m^2\:(2\:d.p.)

<u>Volume</u>

\sf \implies Vol.=area\:of\:base \times height=\left(\dfrac{3\sqrt{391}}{4}\right) \times 6=88.98\:\:m^3\:(2\:d.p.)

<h3><u>Question 8</u></h3>

<u>Lateral Surface Area</u>

The bases of a hexagonal prism are the pentagons.

Therefore, the Lateral Surface Area (L.A.) is the total surface area excluding the areas of the pentagons (bases).

\implies \sf L.A.=5(5 \times 6)=150\:\:cm^2

<u>Total Surface Area</u>

Area of a pentagon:

\sf A=\dfrac{1}{4}\sqrt{5(5+2\sqrt{5})}a^2

where a is the side length.

Therefore:

\implies \sf A=\dfrac{1}{4}\sqrt{5(5+2\sqrt{5})}\cdot 5^2=43.01\:\:cm^2\:(2\:d.p.)

Total surface area:

\sf \implies T.A.=2\:bases+L.A.=2(43.01)+150=236.02\:\:cm^2\:(2\:d.p.)

<u>Volume</u>

\sf \implies Vol.=area\:of\:base \times height=43.011193... \times 6=258.07\:\:cm^3\:(2\:d.p.)

8 0
2 years ago
How long does it take to travel 300 miles at 15 miles per hour
bearhunter [10]
It takes 20 miles per hour to travel 300 miles
8 0
3 years ago
Read 2 more answers
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kvv77 [185]
B = g + 12
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Replace the b in the second equation with
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Divide by 2
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b= 56 + 12
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3 years ago
At an automobile plant, each car is inspected by 34 different workers before it is shipped to a dealer. One day, workers perform
nirvana33 [79]

Answer:  285

Step-by-step explanation:\

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8 0
3 years ago
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slega [8]
The answer is neither 108 or 900, but it is V = 1357.17

To solve, use the formula for the volume of a cone:
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fill r with 6 and h with 36

\frac{ \pi (6)^2(36)}{3}

When you solve that, you get 1357.17
5 0
3 years ago
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