m4maths Maths Puzzle

Total no. of words of 5 letters formed by letters of the word BOMBAY.
[You should use only 5 letters out of 6 letters of the word BOMBAY]

Read Solution (Total 6)

m4maths Other Question
You have nine balls, three of which are slightly heavier, and three of which are slightly lighter than the normal three. All three balls in each group has the same weight. All nine balls are identical otherwise. Your mission is to determine the group of every ball using a pair of scales.

How many weighings are needed in order to ensure the accomplishment of your mission? Pls check the solution for puzzle

Total no. of words of 5 letters formed by letters of the word BOMBAY.
[You should use only 5 letters out of 6 letters of the word BOMBAY]

solution given is ..................
.....
(1st case all the letters are different
total no. of words of this category = 5*4*3*2*1 = 120
2nd case B comes twice and 3 others
total no. of words of this category = 5*4*3*2*1/2*1 = 60
so total words = 120+60 = 180)

I think answer should be 360
as
solution should be

1st case all the letters are different
total no. of words of this category = 5*4*3*2*1 = 120
2nd case B comes twice and 3 others
total no. of words of this category = 4*(5*4*3*2*1/2*1) = 60*4=240 because there will be 4 combinations of such words.
so total words = 120+240 = 360

pls excuse me if I am wrong.