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.
The slope is 0.1
To find a perpendicular slope, find the negative reciprocal.
The reciprocal of 0.1 is 10
The negative of 10 is -10
Final answer:-10
Since Anna is either grouping them as single rock or as group of 10, we need to find the maximum number of groups of 10 as follows: 38/10 = 3.8
This means that Anna can make maximum 3 groups of 10 rocks.
Based on this, the different ways to group the rocks are as follows:
- 3 groups of 10 and 8 (which are calculated as: 38-30) single rocks
- 2 groups of 10 and 18 (which are calculated as: 38-20) single rocks
- 1 group of 10 and 28 (which are calculated as: 38-10) single rocks
- 0 group of 10 and 38 (which are calculated as: 38-0) single rocks
Answer: 2 over 3 = 5 over 6 and the other answer is 6 over 6
Step-by-step explanation: Hope this helps