Tracy received a score of 85% on her quiz. If Tracey answered 9 questions incorrectly, how many questions were on her quiz?
2 answers:
You might be interested in
Answer:
a
Step-by-step explanation:
r = 2.5 in
V = 4(3.14)/3 =
We have:
Thus:
Adding
gives:
Factoring gives:
Thus, we have:
or
.
Note that because
, there will be no solutions 
of the form 
for positive integer 
and solution 
. So we find the basic values of 
giving 
.
For with positive , 
(this can be seen easily from the unit circle. But 
, a contradiction. So we examine the case in which .
In this case,
. So this is the only solution to this equation.
Substituting this back in, we have
, as desired. So this is a valid solution.
Thus,.
Thus:
Adding
Factoring gives:
Thus, we have:
or
Note that because
For
In this case,
Substituting this back in, we have
Thus,