(I). Kamal is available at home from 12 noon to 4 p.m. on Tuesday, Thursday and Sunday.
(II). His younger brother Navin is available at home on Monday, Thursday, Friday and Sunday between 10 a.m. to 2 p.m.
(III). The eldest brother Rajiv is available between 9 a.m. to 12 noon on Monday, Wednesday and Thursday and 2 p.m. to 4 p.m. on Friday, Saturday and Sunday.
At a time, on which day of a week all the three brothers are available at home ?
We prepare a table as under :
|9 a.m. to 10 a.m.||R||R||R|
|10 a.m. to 12 noon||N, R||R||
|12 noon to 2 p.m.||N||K||K, N||N||K, N|
|2 p.m. to 4 p.m.||K||K||R||R||K, R|
Clearly, all the three brothers are not available at the same time on any day of the week.