00:01
Here in question, an arithmetic progression starts with a positive fraction and every alternate term is an integer.
00:10
If the sum of first 11 terms is 33, then the fourth term is what? so we want to find the fourth term and in the question we are given the sum of first 11 terms.
00:23
Okay, so we know that the first end terms.
00:29
First in terms sum of first end terms of an arithmetic sequence is n by 2 n by 2 into 2 a plus n minus 1 n minus 1 into d so this is the sum of n terms of an arithmetic progression okay so we in the question this is given that first 11 terms sum of first 11 terms is given so s 11 is equal to 11 by 2 into 2 a plus n minus 1 into d that is n is 11 minus 1 which is equal to 10 into d here a is the first term and d is the common difference which is equal to given as 33 so which is equal to 33 now we can rearrange the equation we can convert this two into this side.
01:39
So 11 into 2a plus 10d is equal to 66.
01:52
Now we can divide 11 in both sides.
01:57
We can divide 11 by both sides.
02:01
So we will get 2a.
02:06
Plus 10 d is equal to 6 now we can take it two as a common difference here so 2 into a plus 5d is equal to 3 into 2 can cut both 2 from the both sides of the question now a plus 5 d is equal to 3.
02:42
So we got an equation.
02:46
Then as every alternate tape is an integer and sum is positive...