99.99% students fail#Use your mind#shorts

In an examination, 35% students failed in Hindi, 45% students failed in English and 20% students failed in both the subjects. What is the percentage of students passing in both the subjects?

In an examination, 49% students failed in English, 36% students failed in Hindi, while 15% failed in both. If total number of passed students is 450, then how many students did appear in the examination?

In an examination of bank P.O., 40% students failed in Mathematics and 30% failed in English, while 20% failed in Mathematics and English both. What percentage of the students passed in both ?

The results of students of a college revealed the following facts. 25% of students failed in Mathematics, 15% of students failed in Chemistry,10% of students failed in both. If a student is selected at random. The probability that he has failed in Mathematics, given that he failed in Chemistry is (i)1/5 (ii)2/3 (iii)3/5 (iv)1/3