In how many ways can 21 books on English and 19 books on Hindi be placed in a row on a shelf so that two books on Hindi may not be together? Choices:
A) 1540
B) 2314
C) 5420
D) 1240
E) 4512
We must place all these books as under:   XEXEX….XEX   There are 21 books on English, 19 books on Hindi   19 places out of 22 can be chosen 22C19=22C3=1540 ways   1540NS: 1540
<result>A</result>
In how many ways can 21 books on English and 19 books on Hindi be placed in a row on a shelf so that two books on Hindi may not be together?