First approach :
The above series can be seen as
1600 , (1600–400) 1200, (1200–300) 900 .
So we see that the values are getting decreased by 400,300 respectively.
Hence the next term in the sequence will be 900–200 = 700.
Other approach could be :
A geometric progression with ratio as 3/4.
1600*(3/4) = 1200
1200*(3/4) = 900
900*(3/4) = 675
Taking the above two approaches in mind,the two possible answers could be 700 or 675
Um- here ya go