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Flauer [41]
3 years ago
5

On a multiple-choice test. Abby randomly guesses on all seven questions. Each question

Mathematics
1 answer:
Murrr4er [49]3 years ago
8 0

Answer:

0.173 probability that she gets exactly three questions correct.

Step-by-step explanation:

For each question, there are only two possible outcomes. Either she guesses the correct answer, or she does not. 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.

Seven questions:

This means that n = 7

Each question has four choices.

Abby guesses, which means that p = \frac{1}[4} = 0.25

Find the probability to the nearest thousandth, that Abby gets exactly three questions correct.

This is P(X = 3).

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

P(X = 3) = C_{7,3}.(0.25)^{3}.(0.75)^{4} = 0.173

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Examine the first two steps used to solve the equation.
bija089 [108]

Answer:

C.

Step-by-step explanation:

Your fractions are missing there fraction bars:

3/4 (20y − 8) + 5 = 1/2 y + 1/4 (20y + 8)  

15y − 6 + 5 = 1/2 y + 5y + 2  

15y − 1 = 11/2 y + 2

A. 11/2y and 2 aren't like terms because one contains the variable y and the other contains no variable

B. The distribute property can't be used there because you don't have 15(y-1) you have 15y-1

C. Subtracting 11/2y sounds like a good step because there is a y term on the opposing side.

15y-1=11/2y+2

Subtracing 11/2y on both sides

9.5y-1=2

That looks pretty good because then you would add 1 on both sides giving:

9.5y =3

Last step would get the y by itself which is dividing both sides by 9.5 giving you 6/19.

D. You could actually do this but it doesn't help you get x by itself.  The equation would look like this: 15/2 y-1/2=11/4 y+1

5 0
4 years ago
Read 2 more answers
Which of the following is a Type I​ error?
Sedaia [141]
Answer:

C. The president rejects the hypothesis that the proportion of students who earn a​ bachelor's degree within six years is 0.398​, ​when, in​ fact, the proportion is 0.398.

Step-by-step explanation:

A type I error occurs if you reject the null hypothesis when it is true.

Now the hypotheses are:

H_0: The proportion is 0.398

H_1: The proportion is less than 0.398

If in actual fact the proportion is 0.398, then the president must not reject the H_0.

This is a correct decision.

If in actual fact the proportion is 0.398, and the president rejects the H_0, then a type I error is committed.

The correct choice is C.
3 0
3 years ago
Consider the curve y=ln(3x-1).let p be the point on the curve where x=2.
liraira [26]
A. Yes you are correct that the gradient at any point is 3/(3x-1). However at point P it would be 3/(3*2-1)=2/5
b. The gradient of the normal would therefore be -5/2
We can use the general formula of an equation to get y-ln(5)=-5/2 (x-2)
Now multiply both sides by 2 to get:
2y-2ln(5)=-5x+10
Now when it crosses the x axis we know that y=0 therefore:
5x=10+2ln(5)
Therefore:
x=2+2/5 ln(5) when y=0
You could find an estimate of this number to be 2.64 (3sf) but this might not be sufficient

4 0
4 years ago
The cost(c)of chicken varies directly as its weigth(w)equation​
dem82 [27]

Answer:

c = kw

Step-by-step explanation:

Given

c varies directly as w

Required

Write the equation

c varies directly as w.

Mathematically, this is represented as:

c\ \alpha\ w

Convert to equation.

c = kw

<em>Where k is the constant of variation</em>

8 0
4 years ago
A store item is originally priced at $80. The item goes on sale at a 25% discount. Two weeks later that sales price is marked do
pishuonlain [190]
I'm pretty sure the answer is 54! hope this helps 
5 0
3 years ago
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