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Arada [10]
3 years ago
5

California is hit every year by approximately 500 earthquakes that are large enough to be felt. However, those of destructive ma

gnitude occur, on average, once a year. Find a) Probability that at least 3 months elapse before the first earthquake of destructive magnitude occurs. b) Probability that at least 7 months elapsed before the first earthquake of destructive magnitude occurs knowing that 3 months have already elapsed.
Expert Answer
Mathematics
1 answer:
Elanso [62]3 years ago
8 0

Answer:

a) The probability that at least 3 months elapse before the first earthquake of destructive magnitude occurs is P=0.7788

b) The probability that at least 7 months elapsed before the first earthquake of destructive magnitude occurs knowing that 3 months have already elapsed is P=0.7165

Step-by-step explanation:

Tha most appropiate distribution to model the probability of this events is the exponential distribution.

The cumulative distribution function of the exponential distribution is given by:

P(t

The destructive earthquakes happen in average once a year. This can be expressed by the parameter λ=1/year.

We can express the probability of having a 3 month period (t=3/12=0.25) without destructive earthquakes as:

P(t>0.25)=1-P(t

Applying the memory-less property of the exponential distribution, in which the past events don't affect the future probabilities, the probability of having at least 7 months (t=0.58)  elapsed before the first earthquake given that 3 months have already elapsed, is the same as the probability of having 4 months elapsed before an earthquake.

P(t>0.58)/P(t>0.25)=P(t>0.33)

P(t>0.33)=1-P(t

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ACT help!!
DaniilM [7]

g) c=1.98w is your answer

w = weight = 5.5

c = cost = 10.89

10.89 = 1.98(5.5)

10.89 = 10.89 (true)

hope this helps

8 0
3 years ago
A CBS News/New York Times opinion poll asked 1,190 adults whether they would prefer balancing the federal budget over cutting ta
nikklg [1K]

Using the <u>normal distribution and the central limit theorem</u>, it is found that there is a 0.0166 = 1.66% probability of a sample proportion of 0.59 or less.

In a normal distribution with mean \mu and standard deviation \sigma, the z-score of a measure X is given by:

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

  • It 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, which is the percentile of X.
  • By the Central Limit Theorem, the sampling distribution of sampling proportions of a proportion p in a sample of size n has mean \mu = p and standard error s = \sqrt{\frac{p(1 - p)}{n}}

In this problem:

  • 1,190 adults were asked, hence n = 1190
  • In fact 62% of all adults favor balancing the budget over cutting taxes, hence p = 0.62.

The mean and the standard error are given by:

\mu = p = 0.62

s = \sqrt{\frac{p(1 - p)}{n}} = \sqrt{\frac{0.62(0.38)}{1190}} = 0.0141

The probability of a sample proportion of 0.59 or less is the <u>p-value of Z when X = 0.59</u>, hence:

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

By the Central Limit Theorem

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

Z = \frac{0.59 - 0.62}{0.0141}

Z = -2.13

Z = -2.13 has a p-value of 0.0166.

0.0166 = 1.66% probability of a sample proportion of 0.59 or less.

You can learn more about the <u>normal distribution and the central limit theorem</u> at brainly.com/question/24663213

7 0
2 years ago
An urn contains 5 white and 10 black balls. A fair die is rolled and that number of balls is randomly chosen from the urn. What
galina1969 [7]

Answer:

Part A:

The probability that all of the balls selected are white:

P(A)=\frac{1}{6}(\frac{1}{3}+\frac{2}{21}+\frac{2}{91}+\frac{1}{273}+\frac{1}{3003}+0)\\      P(A)=\frac{5}{66}=0.075757576

Part B:

The conditional probability that the die landed on 3 if all the balls selected are white:

P(D_3|A)=\frac{\frac{2}{91}*\frac{1}{6}}{\frac{5}{66} } \\P(D_3|A)=\frac{22}{455}=0.0483516

Step-by-step explanation:

A is the event all balls are white.

D_i is the dice outcome.

Sine the die is fair:

P(D_i)=\frac{1}{6} for i∈{1,2,3,4,5,6}

In case of 10 black and 5 white balls:

P(A|D_1)=\frac{5_{C}_1}{15_{C}_1} =\frac{5}{15}=\frac{1}{3}

P(A|D_2)=\frac{5_{C}_2}{15_{C}_2} =\frac{10}{105}=\frac{2}{21}

P(A|D_3)=\frac{5_{C}_3}{15_{C}_3} =\frac{10}{455}=\frac{2}{91}

P(A|D_4)=\frac{5_{C}_4}{15_{C}_4} =\frac{5}{1365}=\frac{1}{273}

P(A|D_5)=\frac{5_{C}_5}{15_{C}_5} =\frac{1}{3003}=\frac{1}{3003}

P(A|D_6)=\frac{5_{C}_6}{15_{C}_6} =0

Part A:

The probability that all of the balls selected are white:

P(A)=\sum^6_{i=1} P(A|D_i)P(D_i)

P(A)=\frac{1}{6}(\frac{1}{3}+\frac{2}{21}+\frac{2}{91}+\frac{1}{273}+\frac{1}{3003}+0)\\      P(A)=\frac{5}{66}=0.075757576

Part B:

The conditional probability that the die landed on 3 if all the balls selected are white:

We have to find P(D_3|A)

The data required is calculated above:

P(D_3|A)=\frac{P(A|D_3)P(D_3)}{P(A)}\\ P(D_3|A)=\frac{\frac{2}{91}*\frac{1}{6}}{\frac{5}{66} } \\P(D_3|A)=\frac{22}{455}=0.0483516

7 0
3 years ago
The cost C of manning household is partly constant and partly varies as the number of people, the cost is 70,000 and for 10 peop
elena-s [515]

Answer:

4.196.754

Step-by-step explanation:

god bless stay safe po

7 0
3 years ago
-/2 points
Rom4ik [11]

Answer:

Part 1) The domain of the quadratic function is the interval  (-∞,∞)

Part 2) The range is the interval  (-∞,1]

Step-by-step explanation:

we have

f(x)=-x^2+14x-48

This is a quadratic equation (vertical parabola) open downward (the leading coefficient is negative)

step 1

Find the domain

The domain of a function is the set of all possible values of x

The domain of the quadratic function is the interval

(-∞,∞)

All real numbers

step 2

Find the range

The range of a function is the complete set of all possible resulting values of y, after we have substituted the domain.

we have a vertical parabola open downward

The vertex is a maximum

Let

(h,k) the vertex of the parabola

so

The range is the interval

(-∞,k]

Find the vertex

f(x)=-x^2+14x-48

Factor -1 the leading coefficient

f(x)=-(x^2-14x)-48

Complete the square

f(x)=-(x^2-14x+49)-48+49

f(x)=-(x^2-14x+49)+1

Rewrite as perfect squares

f(x)=-(x-7)^2+1

The vertex is the point (7,1)

therefore

The range is the interval

(-∞,1]

6 0
3 years ago
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