 Hi friends, I am Poorfa and today we will work out the following question. If A and B are two events such that probability of A is equal to 1 upon 4, probability of B is equal to 1 upon 2 and probability of A intersection B is equal to 1 upon 8, find probability of not A and not B. Let us begin with the solution now. Now we have to find probability of not A and not B. That is we have to find probability of A complement intersection B complement. Now we know that A complement intersection B complement is equal to A union B whole complement. Thus we get probability of A complement intersection B complement is equal to probability of A union B whole complement and this is equal to 1 minus probability of A union B. Since we know that probability of A complement is equal to 1 minus probability of A, thus we have to now find 1 minus probability of A union B. Now we are given that probability of A is equal to 1 upon 4, probability of B is equal to 1 upon 2 and probability of A intersection B is equal to 1 upon 8. Now we know that probability of A union B is equal to probability of A plus probability of B minus probability of A intersection B. This is equal to probability of A which is equal to 1 upon 4 plus probability of B which is equal to 1 upon 2 minus probability of A intersection B which is equal to 1 upon 8. So we get probability of A union B is equal to 5 upon 8. Now we have just seen that probability of not A and not B is equal to 1 minus probability of A union B. This is equal to 1 minus probability of A union B which is equal to 5 upon 8 and this is equal to 3 upon 8. So we have got probability of not A and not B is equal to 3 upon 8. So we have got our answer as 3 upon 8. Hope you have understood the solution. Bye and take care.