Please help me! I will mark Brainliest if you answer all of these portfolio questions!

Jane must get at least three of the four problems on the exam correct to get an A. She has been able to do 80% of the problems o

NISA [10]

Answer:

a) There is n 81.92% probability that she gets an A.

b) If she gets the first problem correct, there is an 89.6% probability that she gets an A.

Step-by-step explanation:

For each question, there are only two possible outcomes. Either the answer is correct, or it is not. This means that we can solve this problem using binomial distribution probability concepts.

Binomial probability distribution

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

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

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

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

And $\pi$ is the probability of X happening.

For this problem, we have that:

The probability she gets any problem correct is 0.8, so $\pi = 0.8$ .

(a) What is the probability she gets an A?

There are four problems, so $n = 4$

Jane must get at least three of the four problems on the exam correct to get an A.

So, we need to find $P(X \geq 3)$

$P(X \geq 3) = P(X = 3) + P(X = 4)$

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

$P(X = 3) = C_{4,3}.(0.80)^{3}.(0.2)^{1} = 0.4096$

$P(X = 4) = C_{4,4}.(0.80)^{4}.(0.2)^{0} = 0.4096$

$P(X \geq 3) = P(X = 3) + P(X = 4) = 2*0.4096 = 0.8192$

There is n 81.92% probability that she gets an A.

(b) If she gets the first problem correct, what is the probability she gets an A?

Now, there are only 3 problems left, so $n = 3$

To get an A, she must get at least 2 of them right, since one(the first one) she has already got it correct.

So, we need to find $P(X \geq 2)$

$P(X \geq 3) = P(X = 2) + P(X = 3)$

$P(X = 2) = C_{3,2}.(0.80)^{2}.(0.2)^{1} = 0.384$

$P(X = 4) = C_{3,3}.(0.80)^{3}.(0.2)^{0} = 0.512$

$P(X \geq 3) = P(X = 2) + P(X = 3) = 0.384 + 0.512 = 0.896$

If she gets the first problem correct, there is an 89.6% probability that she gets an A.

3 0

3 years ago

Simplify the expression (7+5)+4•13-2

Yakvenalex [24]

Pemdas

Parentheses exponents multiplication divide add subtract (7+5)=12

12+4•13-2 4•13= 52

12+52-2
64-2

The answer is 62

7 0

3 years ago

Read 2 more answers

An equation ___ has one solution <br><br> A. Always <br> B. Sometimes <br> C. Never

Doss [256]

im am pretty sure it is b.sometimes because an equation can have more then one answer

4 0

3 years ago

Given that a trapezoid has the following dimensions, find the area. Area = ________ units2

rjkz [21]

The formula for the area of a trapezoid is A = a+b/2 * h. So just plug in the dimensions.
A = 5 + 3/2 * 5
A = 8/2 * 5
A = 4 * 5
A = 20 units²
I hope this helps love! :)

8 0

3 years ago

Look at each equation and possible solution. Is the solution correct? Select Yes or No for each equation.

oksano4ka [1.4K]

Answer:

yes

Step-by-step explanation:

7 0

3 years ago