Ali was writing an exam. There where 4 passages of equal length(in words) and they have 5,8,8,6 questions respectively. Ali can answer exactly 12 questions in the time he takes to read any one of the four passages. Assume that his rate of reading and answering the questions remain the same across the 4 passages. By what % should Ali increase his reading speed in order to cut down his total time spent by 10% ?

1) 20
2) 18.5
3) 15.625
4) 15
5) 25