The marks obtained by 12 students in an examination (out of 50) are given below.
18, 35, 2, 27, 40, 0, 21, 33, 27, 8, 36, 23.
Find the mean marks.

Hint: Mean is the average of a data. It helps us give an idea of the overall data. To find the mean of the given data we have to first find the sum of all the marks scored by 12 students. After that we have to divide this sum by the count of marks that is the total number of values for marks considered which here is 12.

Complete step-by-step answer:
The marks scored by the 12 students are 18, 35, 2, 27, 40, 0, 21, 33, 27, 8, 36 and 23.
To find their mean, we will have to first find their sum total which will be given as \[18 + 35 + 2 + 27 + 40 + 0 + 21 + 33 + 27 + 8 + 36 + 23 = 270\].
Now that we have the sum of marks scored by the 12 students, we can divide this by the number of marks considered that is 12. So, the mean of the marks scored is given by \[\Rightarrow \dfrac{{270}}{{12}} = 22.5\].
Hence, the mean for the following data comes out to be 22.5 marks scored per student.

Note: Here, if we notice, one of the students has scored 0 marks. Most of the students make the mistake of discarding this value and dividing the sum by 11 only, which is incorrect because we have to find the average of marks scored by 12 students and one of the students has scored 0 marks, so we must consider it while counting the number of values for marks scored.