a1+a2+.....+aN=300N 6a1+a2+.....+aN=400N 5a1=100N a1=20N As the given sequence of numbers is non-decreasing sequence, N can take values from 2 to 15. N is not equal to 1 , if N=1, then average of N numbers is 300 wouldn't satisfy. Therefore, N can take values from 2 to 15 , i.e. 14 values.