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1 year ago

Suppose that X is a random variable with mean and variance both equal to 20. What can be said about P{0 ≤ X ≤ 40}.

Mathematics

1 answer:

Dennis_Churaev [7]1 year ago

5 0

Answer:

$P(0 \leq X \40) = \frac{19}{20}$

Step-by-step explanation:

We know that:

$P(|X - 20| < 20) + P(|X - 20| \geq 20) = 1$

$P(0 \leq X \leq 40) = P(0-20 \leq X-20 \leq 40-20) = P(-20 \leq X \leq 20) = P(|X - 20| \leq 20)$

$P(|X - 20| \leq 20) = 1 - P(|X - 20| > 20) = 1 - \frac{20}{20^{2}} = \frac{19}{20}$

$P(0 \leq X \40) = \frac{19}{20}$

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Answer:

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Step-by-step explanation:

Naturally, the answer should be a number equal or higher than 20, because up to 20 persons, each one pays the same. Lets define a revenue function for x greater than or equal to 20.

f(x) = x*(40-(x-20)) = -x²+60x

Note that f multiplies the number of persons by how much would they pay (here, assuming that there are more than 20).

f is quadratic with negative main coefficient and its maximum value will be reached at the vertex.

The value of the x coordinate of the vertex is -b/2a = -60/-2 = 30

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1 year ago

Shana, who lives in Canada, and Pearl, who lives in Pennsylvania, were discussing the weather. Shana complained about the cold t

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Answer:

<h3>Negative (negative 20) = 20</h3>

Step-by-step explanation:

Given Shana temperature = -20°C

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Hence the correct way to represent "the opposite of Shana's temperature is equal to Pearl's

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2 years ago

Ramon wants to plant cucumbers and tomatoes in his garden. He has room for

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Answer:

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Step-by-step explanation:

Let number of cucumber be c and number of tomatoes be t

Since he has room for 16 plants, we can write:

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He wants to plant 3 times as many cucumbers as tomatoes. We can write:

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We can substitute this in 1st equation and solve for t:

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1 year ago

Read 2 more answers

You and a group of friends are going to a five-day outdoor music festival during spring break. You hope it does not rain during

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Answer:

The probability of not rain during the entire festival is 0.19

Step-by-step explanation:

The Complement Rule states that the sum of the probabilities of an event and its complement must equal 1.

In this case we have the probability of raining of each day, we need the probability of NOT raining.

First day= 45% chance of rain, the complement is 55%

Second day 55% chance of rain, the complement is 45%

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Fourth day a 10% chance of rain, the complement is 90%

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