He has 28 blue marbles 15+12-55=28
Using permutations and the probability concept, it is found that there is a 0.0417 = 4.17% probability that Nia is chosen as president.
- A probability is the <u>number of desired outcomes divided by the number of total outcomes</u>.
- As there are different roles, the order in which the students are chosen is important, hence, the <em>permutation </em>formula is used to solve this question.
Permutation formula:
The number of possible permutations of x elements from a set of n elements is given by:
Desired outcomes:
- For the other roles, 3 students from a set of 23, hence:

Total outcomes:
4 students from a set of 24, hence:

Then:

0.0417 = 4.17% probability that Nia is chosen as president.
To learn more about probabilities, you can take a look at brainly.com/question/24437717
To answer this question, we need a strong understanding of what "contrapositive" means:
The contrapositive of a conditional statement flips the hypothesis and conclusion, and makes both negative.
Here is an example:
Conditional Statement: If I am sick, then I stay home from school.
Hypothesis: I am sick, Conclusion: I stay home from school
Contrapositive: If I do not stay home from school, I am not sick.
What would be the contrapositive in our conditional statement?
Conditional Statement: <span>If an angle is a right angle, then the angle measures 90°
Contrapositive: If the angle does not measure 90</span>°, then the angle is not a right angle.
In this case, both the conditional statement and the contrapositive are true. We know this because a 90° angle and a right angle are the same thing.
( –6m^7 + 20m^6<span>) ÷ 2m^4 = ???
as you know
</span> –6m^7 + 20m^6 = 2m^4 (-3m^3 + 10m^2)
[2m^4 (-3m^3 + 10m^2) ] / 2m^4 (2m^4 is canceled out)
= -3m^3 + 10m^2
answer is B. –3m^3 + 10m^2
A circle is 1 revolution or 360 degrees. So, the probability that a dart <span>will land in the unshaded region is
</span>

The answer is
67%.