The intensity of a sound wave gets reduced by `20%` on passing through a slab. The reduction intensity on passage through two such consecutive slabs

Explanation

Reduction in intensity after through first slab `= 20%`
Reduction in intensity after passing through second slab `= 20 %` of the intensity left (i.e., 80 %) after passing through first slab `= (1)/(5) xx 80% = 16 %`
Total reduction in intensity after passing through two consecutive slabs `= 20 % + 16 %`
=`36 %`.