S.I. for first year = Rs. 400
S.I. on Rs .400 for 1 year =Rs. 32
∴ Rate = (interest x 100)/(principle x time) = (100 x 32)/(400 x 1) = 8%
Hence, the difference for 3rd year is S.I.on Rs. 832
= Rs.(832 x 8/100)
= Rs. 66.56
∴ Total difference = Rs.(32 + 66.56)
= Rs. 98.56