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2 years ago

What is the value of n?

Mathematics

1 answer:

vitfil [10]2 years ago

3 0

9(n+7) = 18(n+1)
9n + 63 = 18n + 18
9n = 45
n = 5

answer
n = 5

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A student takes an exam containing 1414 multiple choice questions. The probability of choosing a correct answer by knowledgeable

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Answer:

0.0082 = 0.82% probability that he will pass

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the students guesses the correct answer, or he guesses the wrong answer. The probability of guessing the correct answer for a question is independent of other questions. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

In this problem we have that:

$n = 14, p = 0.3$ .

If the student makes knowledgeable guesses, what is the probability that he will pass?

He needs to guess at least 9 answers correctly. So

$P(X \geq 9) = P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12) + P(X = 13) + P(X = 14)$

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 9) = C_{14,9}.(0.3)^{9}.(0.7)^{5} = 0.0066$

$P(X = 10) = C_{14,10}.(0.3)^{10}.(0.7)^{4} = 0.0014$

$P(X = 11) = C_{14,11}.(0.3)^{11}.(0.7)^{3} = 0.0002$

$P(X = 12) = C_{14,12}.(0.3)^{12}.(0.7)^{2} = 0.000024$

$P(X = 13) = C_{14,13}.(0.3)^{13}.(0.7)^{1} = 0.000002$

$P(X = 14) = C_{14,14}.(0.3)^{14}.(0.7)^{0} \cong 0$

$P(X \geq 9) = P(X = 9) + P(X = 10) + P(X = 11) + P(X = 12) + P(X = 13) + P(X = 14) = 0.0066 + 0.0014 + 0.0002 + 0.000024 + 0.000002 = 0.0082$

0.0082 = 0.82% probability that he will pass

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2 years ago

Need help ! Which equation could be represented by the number line?

DanielleElmas [232]

Answer:

I think its b

Step-by-step explanation:

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3 years ago

Which of the Following is a solution to 7x-6y=19 (-5,-3) ,(7,5), (-4,0) (1,-2)

Korolek [52]

Answer:

(1,-2)

Step-by-step explanation:

Choose any value for x that is in the domain to plug into the equation.

Choose 0 to substitute in for x to find the ordered pair.

(0, -19/6)

Choose 1 to substitute in for x to find the ordered pair.

Remove parentheses.

y= -19/6 + 7(1)/6

Simplify

y=2

Use the

x and y values to form the ordered pair.

(1,−2)

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3 years ago

20% of city employees ride the bus to work. This is up 10% from last year. What percent of employees rode the bus to work last y

Pepsi [2]

Answer:

18.18% of employees rode the bus to work last year

Step-by-step explanation:

This question can be solved using a rule of three.

Last year, a proportion of x employees riding the bus was 100% = 1.

This year, 20% = 0.2 ride the bus, which is 100 + 10 = 110% = 1.1 of last year.

0.2 - 1.1

x - 1

$1.1x = 0.2$

$x = \frac{0.2}{1.1}$

$x = 0.1818$

0.1818*100 = 18.18%

18.18% of employees rode the bus to work last year

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3 years ago

A tortoise moves forward 15 meters in one hour. It turns around and crawls 10 meters in the

schepotkina [342]

Answer:

Below.

Step-by-step explanation:

15+10+8=33.

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2 years ago

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