Question

the number of ways in which three letters can be posted in two post boxes if any number of letters can be posted in a post box are​

Answer 1

Answer:

We can post the first letter in 4 ways and 2nd too in 4 ways, as well as the third. Therefore the total number of ways is 4 x 4 x 4 = 64.

All the three letters can be posted in any of the four letter boxes in 4 ways.

Hence the corresponding number when all are not posted in the same letter box is 64 - 4 = 60.

Answer 2

Answer:

Step-by-step explanation:

First letter could be sent from ANY of the seven postboxes - 7 (7 options);

Second letter could be sent from the SIX postboxes left - 6 (6 options);

Third letter could be sent from the FIVE postboxes left - 5 (5 options);

Total # of ways =7*6*5=210