What does an average and standard deviation on a test mean? Is that a C+ or a C?

Average is like C on a test


standard deviation would be the + and - of those grades


If your teacher grades on a regular standard normal distribution curve or bell curve





let me give an example


say 65 is the average


deviation is 5


so for a plus is like 5 plus 65 or a score of 70 and a minus is 60


and 2*deviation would be the next grades and 3*deviations the next if the grades were following a standard normal distribution, then the median and mean would be equal as well





standard deviation measures the spread of grdes if its small then most people got the same grade, for within one standard deviation (the plus or minus) would be 68% of the class, so in the example 68% of the class scored between 60 and 70, and within 2 deviations or 55 and 75 is where 95% scored and for within 3 is 98%





But More or less the mean and deviation doesnt tell you what grade it will be, most likely your teacher will have their own grade system and the average and deviation just tells you how did compared to the majority of the class

What does an average and standard deviation on a test mean? Is that a C+ or a C?
I don'n know what you mean for the C nor the C+, but the average, which is the sum of all measurements taken on a particular object divided by the number of repetitions.


For example:


A comb was measure on two diferent occasions (two repetitions) and they got these results:


Measure 1=2.5


Measure 2=2.3


Average of the lipstick is 4.8/2= 2.4





For the Standard deviation to be calculated, begins with the calculation of the aritmetic mean. After the mean is determined, the residuals are found. These residuals are squared and the sum of those squares, symbolized by the v², is calculated.


To get v (residual), you need to subtract every measure to the average, and the formula is:


Measure # - Average =v


Residual of Measure1 (v) 1=2.5-2.4=0.1


Residual of Measure 2(v) 2=2.3-2.4=-0.1





To get the v²


Measure1 (v)²=0.1²=0.010


Measure 2 (v)²=-0.1²=0.010


Sum of all measurements (Σv²) =0.010+0.010=0.020


Now the standard deviation formula can be solved:


σ=sqr(Σv²/n-1)


where: Σv² =0.020


and n is the number of measurements


σ=sqr(0.020/2-1)


σ=sqr(0.020)


σ=0.14 That will be the standard deviation for the two measurements of the comb I just invented above.


I could've not answer you,with so little information, but since you wanted to know what does a standard deviation and average meant, I just decided to get myself a headache right now, LMFAO! Hope this helps, cause, as for now, I'm going off to bed. Tah-Tah!


PS- Writing here is good when I'm lacking of spanish words, Peace!