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.

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

And p is the probability of X happening.
Seven questions:
This means that 
Each question has four choices.
Abby guesses, which means that 
Find the probability to the nearest thousandth, that Abby gets exactly three questions correct.
This is P(X = 3).


⁴√400 / ⁴√5 = 400^¼ / 5^¼
= (5 x 2²)² / 5^¼
= 5² x 2⁴ / 5^¼
= ⁴√5^7 x 2⁴
Answer:
x=141
Step-by-step explanation:
(n-2)•180 = Sum of all the interior angles
n = # of sides
(7-2)•180
5•180
900= Sum of all the interior angles
Add all the angles and equal them to 900
125+122+131+x+7+x+107+x-15=900
Add all the numbers up first on the left side
477+3x=900
3x=423
x=141