3SO THIER CLOSED IN 1 END AND OPEN IN OTHER RITE ........
L = λ/4 ...............[FUNDEMENTAL]
4L = v/f ...........
f = v/4L .......
f1 - f2 = 5 = v/4(1/L2 - 1/L1) ..........
v(L1 - L2)/L1L2 = 20 ...............
TAKE L1 = 51/50L2 ..............
v(L2)/51(L2)2 = 20 ..........
v/51(L2) = 20 ......................
L2 = v/1020 ...................
L1 = 51/50(v/1020 ) ................
f1 = v/4L1 ....
f2 = v/4L2 .......
PUT VAL. OF L1 , L2 ,,, ULL GET ANS .......
DONT WORRY IF VEL OF SOUND IS NOT GIVEN IT GETZ CANCELLED ....[1]