You need to understand that you're solving for the average, which you already know: 90. Since you know the values of the first three exams, and you know what your final value needs to be, just set up the problem like you would any time you're averaging something.
Solving for the average is simple:
Add up all of the exam scores and divide that number by the number of exams you took.
(87 + 88 + 92) / 3 = your average if you didn't count that fourth exam.
Since you know you have that fourth exam, just substitute it into the total value as an unknown, X:
(87 + 88 + 92 + X) / 4 = 90
Now you need to solve for X, the unknown:
87
+
88
+
92
+
X
4
(4) = 90 (4)
Multiplying for four on each side cancels out the fraction.
So now you have:
87 + 88 + 92 + X = 360
This can be simplified as:
267 + X = 360
Negating the 267 on each side will isolate the X value, and give you your final answer:
X = 93
Now that you have an answer, ask yourself, "does it make sense?"
I say that it does, because there were two tests that were below average, and one that was just slightly above average. So, it makes sense that you'd want to have a higher-ish test score on the fourth exam.
Answer:
511
Step-by-step explanation:
ok
Answer: 
Step-by-step explanation:
<h3>
The complete exercise is: "Line segment YV of rectangle YVWX measures 24 units. What is the length of line segment YX?"</h3><h3>
The missing figure is attached.</h3>
Since the figure is a rectangle, you know that:
Notice that the segment YV divides the rectangle into two equal Right triangles.
Knowing the above, you can use the following Trigonometric Identity:
You can identify that:
Therefore, in order to find the length of the segment YX, you must substitute values into and then you must solve for YX.
You get that this is:
