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lyudmila [28]
2 years ago
15

You have a friend who claims to psychic. You don't believe this so you test your friend by flipping a coin 20 times and having h

im predict whether each flip is heads of tails. If you are right, and your friend is NOT psychic, then the probability of guessing correctly on each flip is .5. Your friend correctly guesses 15 out of the 20 flips. What is the probability of your friend correctly guessing 15 or more out of 20 flips if he is NOT really psychic? (Give your answer to at least 3 places past the decimal point)
Mathematics
1 answer:
Andre45 [30]2 years ago
8 0

Answer:

Given that your friend in not really psychic, he has a probability of P=1.5% of guessing right 15 out of 20 coin flips.

Step-by-step explanation:

We have a binomial distribution problem.

We have to calculate the probability of correctly guessing 15 out of 20 flips of a coin (probability of success for every trial: p=0.5).

We can calculate that with the binomial distribution formula:

P(x)=\frac{n!}{x!(n-x)!}p^x(1-p)^{n-x} \\\\P(15)=\frac{20!}{15!*5!}0.5^{15}*0.5^5\\\\P(15)=15504*0.5^{20}=15504* 0.00000095367 = 0.015

Then we can conclude that, given that your friend in not really psychic, it has only 1.5% of guessing right 15 out of 20 coin flips.

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Trevor is analyzing a circle, y2 + x2 = 100, and a linear function g(x). Will they intersect?
lakkis [162]
Given a circle described by the equation:
y^2+x^2=100
and a function g(x) given by the table
\begin{center}
\begin{tabular}{ |c |c |c }
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 -1 & -22 \\
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1 & -18   
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The function g(x) describes a straight line with the equation:
\frac{y-y_1}{x-x_1} = \frac{y_2-y_1}{x_2-x_1}  \\  \\  \frac{y-(-22)}{x-(-1)} = \frac{-20-(-22)}{0-(-1)}  \\  \\ \frac{y+22}{x+1} = \frac{-20+22}{0+1} = \frac{2}{1}  \\  \\ y+22=2(x+1)=2x+2 \\  \\ y=2x-20

To check if the circle and the line intersects, we substitute the equation of the line into the equation of the circle to see if we have a real solution.
i.e.
y^2+x^2=100 \\  \\ (2x-20)^2+x^2=100 \\  \\ 4x^2-80x+400+x^2=100 \\  \\ 5x^2-80x+300=0 \\  \\ x^2-16x+60=0 \\  \\ (x-6)(x-10)=0 \\  \\ x-6=0 \ or \ x-10=0 \\  \\ x=6 \ or \ x=10

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2 years ago
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The  the probability that a camera has a lens defect given that it has a charging defect is calculated as:

P(L|C)=\frac{P(C)P(L)}{P(C)}\\\\=\frac{0.025\times 0.03125}{0.03125}\\\\=0.025

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2 years ago
Prove the following using a proof by contradiction:The average of four real numbers is greater than or equal to at least one of
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Answer:

By contradiction it can be proved that:

Average of four real numbers will be greater than or equal to at least one of the four real numbers.

Step-by-step explanation:

Method of contradiction means we assume opposite to the facts to be proved and then we contradict our assumption.

As a result, we prove the fact.

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Now, let us add all of them:

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Answer:

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⇒ x+83-83=180-83

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⇒ x=97 degrees

The measure of angle JKL in the triangle is of 97 degrees.

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2 years ago
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