 Hello and welcome to the session. In this session we discussed the following question which says find the third proportional to 4 and 8. Now if we have that A is to B is proportional to B is to C then C is called the third proportional to A and B and also the C would be called the fourth proportional to AB and B. This is the key idea for this question. Let's move on to the solution now. We take let the third proportional to 4 and 8 be equal to X then we have the fourth proportional to 4, 8 and 8 is also equal to X. That is we have 4 is to 8 is proportional to 8 is to X and so this means that the product of extremes that is 4 multiplied by X is equal to the product of the means that is 8 multiplied by 8. This gives us X is equal to 8 multiplied by 8 upon 4. Now 4 2 times is 8 so this is equal to 8 into 2 which means that X is equal to 16. Thus we have the third proportional to 4 and 8 is 16. So this completes this session. Hope you have understood the solution for this question.