Answer:
82
Explanation:
If the class average needs to be 71, the mean has to be 71. (Mean is a type of average btw).
Formula to find the mean: Add up all the values and divide by the amount of values there are.
Since there is an unknown we need to work backwards to find out what it must be so that the mean is 71.
This is what the equation would look like.
(71 + 56 + 77 + 69 + x) / 5 = 71
But, to find x we need to make x the subject of the equation, this means that x needs to be on its own at one side of the equals sign so that we have a formula that equals to x. Then we can just do that formula and work it out.
Making x the subject:
71 + 56 + 77 + 69 + x / 5 = 71
1. Move the '/5' to the other side of the equation. This means it will become a '×5'
71 + 56 + 77 + 69 + x = 71×5
2. Get rid of all the other numbers. We can do this all at once by adding them all together and bringing them to the other side.
273 + x = 71×5
x = (71×5) - 273
Now we have our formula
Working this out:
x = (71×5) - 273
x = 355 - 273
x = 82
The fifth student scored an 82.
Let's check to see
In order to this, find the mean of the values and see if we get 71 to match the question.
(72 + 56 + 77 + 69 + 82) / 5 = 71
356 / 5 = 71.2
Correct!