Maria is 23rd from the top and 37th from the bottom in his class. He is 18th from the top and 23rd from the bottom among the students who passed. How many students failed?
19
Total no. of students = [Maria's place from the top + Maria's place from the bottom] -1
= [23 + 37] - 1 = 59
No. of students who passed
= [Maria's place from the top + Maria's place from the bottom] -1
= [18 + 23] - 1 = 40
∴ Number of failed students = 59 - 40 = 19