10	11	15	24	40
6	(a)	(b)	(c)	(d)	(e)
What will come in place of (c)?

As per the details in the question the series is in the form of
First series :-
First term = 10
Second term = First term + 1²
? Second term = 10 + 1² = 10 + 1 = 11
Third term = Second term + 2²
? Third term = 11 + 2² = 11 + 4 = 15
similarly , we can find the all others terms .
Second series :-
First term = 6
Second term = First term + 1²
? Second term = 6 + 1² = 6 + 1 = 7
Third term = Second term + 2²
? Third term = 7 + 2² = 7 + 4 = 11
Fourth term = Third term + 3²
? Fourth term = 11 + 3² = 11 + 9 = 20
Hence , the place value of ( c ) is 20 .