Question:
Harpreet tosses two different coins simultaneously (say, one is of Re 1 and other of Rs 2). What is the probability that he gets at least one head?
Solution:
GIVEN: Harpreet tosses two different coins simultaneously (Re1 and Rs2)
TO FIND: Probability of getting at least one head.
When two coins are tossed then the outcome will be
TT, HT, TH, HH.
Hence total number of outcome is 4.
At least one head means 1H or 2H
Hence total number of favorable outcome i.e. at least one head is 3
We know that PROBABILITY = 
Hence probability of getting at least one head = 