⇒ common ratio =r=3 and the given sequence is geometric sequence. Where an is the nth term, a is the first term and n is the number of terms. ⇒ 12th term is 708588 .
(May be wrong for some other users, although it's correct for me.)
A: 292892 b: 2972 c: 9272726: d: 196373
Yes.
9m-3m=1+19
6m=20
m=20/6=10/3
Solution:
we are given that
In a class, every student knows French or German (or both).
15 students know French, and 17 students know German.
Suppose there are x student who knows both French and German.
Then Total number of student in the class will be 
But to guess the largest possible number of student in the class we can assume x=0
Hence the largest Possible number of Student in the class=32
15.5 times 5.26 is 81.53 and 80 is closest to that so D