my approach was that i took the first series as 1,2,3,4,5,6,7,8,9,10 and the second one as 0,2,4,6,8,10,12,14,16,18 as 0 is also considered as a even number then it says sum of the second series will result in 210 but my result is 90 so the multiplying factor will be 210/90 = 7/3 and the average of the original sequence without a10 will be 5 then the answer coming out to be multiplying factor5 = 7/35=11.666 closes to 11.5 ! but the answer given is 11 and i cant find any mistake in my method which i applied here ? where is the mistake happening ? review it.
Please log in to comment and participate in discussions.
Academic discussion and doubt solving for: Progression & Series, Inequalities, Linear Equation, Functions, Modulus, Minima & Maxima, Polynomials, Identities, Indices
Create an account to join our community and participate in discussions.
Hay Padhai
The problem with your method is that there are two different sequences, and since neither of the sequences is a simple multiple (like 2a), there is some subtraction involved in them. So your method will not give you the correct relation as the ratio is for the 2nd sequence, not for the first one.
If you want to approach this question in this specific way, then you need to find the ratio for the 1st sequence.
Alternatively, I would suggest you use the formula for the Sum of A.P. in this question.
Got it thank you