In the given question, it has been given that the number of students passing the examination is 3257. Also it is given in the question that the percentage of students that passed the examination is 21%. It is required to find out the number of students appearing in the examination.
Let us assume that the number of students appearing in the examination = X
Then,
The number of students passing the examination = 21X/100
So we get the equation
21X/100 = 3257
21X = 3257 * 100
21X = 325700
X = 325700/21
= 15509.52
So the number of students appearing in the examination is 15510 approx.