3.09% is the change from 388 to 400
Calculation steps:
[( 400 - 388 ) ÷ 388] x 100 = 3.09%
Formula
Percentage change = [(400 - 388) / 388] x 100
Subtract the new number by the original number
400 - 388 = 12
12 ÷ 388 = 0.030927835051546393
0.030927835051546393 x 100 = 3.09%