Aptitude - Odd Man Out and Series - Discussion

41 + 2 = 43.
43 + 4 = 47.
47 + 6 = 53.
53 + 8 = 61.
61 + 10 = 71.
71 + 12 = 83.
All even numbers added starting from +2,+4,+6,+8,+10,+12..
So 73 is the correct answer.

For anyone saying even 73 can be the answer, no it can't
if the series were;

41,43,47,53,61,71,73,97 the answer would have been 73.
but the series is:
41,43,47,53,61,71,73,81.

The last number 81 doesn't go with the 2,4,6,8,10,12,14.
Addition series.
So the answer is 81, with the explanation that 81 is a composite number.

I think 73 is the answer.

It's also in the order added by even numbers starting from 2, 4, 6, 8, 10, 12, 14.

So instead of 81, it should be 85.

Hence, 81 is the odd one out.

Yes, 73 is the right answer.

It can be solved in this way too.

41+(1*1)+1 = 43
43+(2*1)+2 = 47
47+(3*1)+3 = 53
53+(4*1)+4 = 61
61+(5*1)+5 = 71
71+(6*1)+6 = 83.

And here 81. So, therefore, it is out of the series.

Yes, you are right, agree with you @Praveen.

@Saurabh.

A number that is divisible only by itself and 1, then we are called prime number.

Read the answer properly, it say that except 81 all are prime number. To all genius.

81 is divisible by 9, so it isn't a prime number. 9x9=81. the rest of the numbers can not be divided into evenly without a remainder. For example 5 is a prime because if you divide it by 2 you will have a remainder. 5 is only divisible by 5 or by 1.

also stated above was the formula: tn= t(n-1)+2n
where n= 1,2,3,4,...etc.
and t= 41,43,47,53,...etc.

If you plug in the numbers it doesn't equal the 2nd term which is 43.
let t= 1st term 41
n= 1

Example with above formula:tn= 41(1-1)+2(1)
41(0)+2 = 2?
I do understand t+2n
41+2(1)= 43
43+2(2)= 47
47+2(3)= 53

I am not trying to be picky, I was really trying to understand.
thanks for the above solutions!