A school has four sections A, B, C and D of Class X students. The results of half-yearly and annual examinations are shown in the table given below:

Result	Number of Students
	Section A	Section B	Section C	Section D
Students failed in both exams	25	22	18	20
Students failed in half-yearly but passed in annual exam	20	25	24	12
Students passed in half-yearly but failed in annual exam	12	15	8	10
Students passed in both exams	15	20	22	18

How many students are there in Class X in the school?

The correct answer is 286.

To find the total number of students in Class X in the school, we need to sum the number of students in all categories across all four sections (A, B, C, and D).

Let us calculate the total number of students in each section:

Section A:
Students failed in both exams = 25
Students failed in half-yearly but passed in annual exam = 20
Students passed in half-yearly but failed in annual exam = 12
Students passed in both exams = 15
Total in Section A = $25+20+12+15=72$

Section B:
Students failed in both exams = 22
Students failed in half-yearly but passed in annual exam = 25
Students passed in half-yearly but failed in annual exam = 15
Students passed in both exams = 20
Total in Section B = $22+25+15+20=82$

Section C:
Students failed in both exams = 18
Students failed in half-yearly but passed in annual exam = 24
Students passed in half-yearly but failed in annual exam = 8
Students passed in both exams = 22
Total in Section C = $18+24+8+22=72$

Section D:
Students failed in both exams = 20
Students failed in half-yearly but passed in annual exam = 12
Students passed in half-yearly but failed in annual exam = 10
Students passed in both exams = 18
Total in Section D = $20+12+10+18=60$

Total Number of Students in Class X:
We add the totals of all four sections:
Total = Total of A + Total of B + Total of C + Total of D
$\text{Total}=72+82+72+60=286$

Therefore, there are a total of 286 students in Class X in the school.