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Option C:
The measure of arc CD is 40°.
Solution:
Given data:
m∠X = 11° and m(arc AB) = 18°
To find the measure of arc CD:
We know that,
<em>Angle formed by two intersecting secants outside the circle is equal to half of the difference between the intercepted arcs.</em>
Multiply by 2 on both sides.
22° = arc CD - 18°
Add 18° from both sides.
40° = arc CD
Switch the sides.
arc CD = 40°
Hence the measure of arc CD is 40°.
Option B is the correct answer.
Answer:
unreadable score = 35
Step-by-step explanation:
We are trying to find the score of one exam that is no longer readable, let's give that score the name "x". we can also give the addition of the rest of 9 readable s scores the letter "R".
There are two things we know, and for which we are going to create equations containing the unknowns "x", and "R":
1) The mean score of ALL exams (including the unreadable one) is 80
so the equation to represent this statement is:
mean of ALL exams = 80
By writing the mean of ALL scores (as the total of all scores added including "x") we can re-write the equation as:
since the mean is the addition of all values divided the total number of exams.
in a similar way we can write what the mean of just the readable exams is:
(notice that this time we don't include the grade x in the addition, and we divide by 9 instead of 10 because only 9 exams are being considered for this mean.
Based on the equation above, we can find what "R" is by multiplying both sides by 9:
Therefore we can now use this value of R in the very first equation we created, and solve for "x":