preyshi wrote:

There are 5 married couples and a group of three is to be formed out of them; how many arrangements are there if a husband and wife may not be in the same group?

if you mean "Arrangements" , its a totally different question.

i assume ,you meant # of ways to select three people so that a couple in not there in a group.

Required answer = total # of ways - # of ways in which a couple are in a group.

1. Total # of ways = 10C3 ( 5 couples...ten people) = 120

2. # of ways a couple can be selected =

5C1 * 8C1 = 40 ways

Select one couple out of the five ..and select one person out of the rest

of the 8.

3. required answer = 120 - 40 = 80 ways
EDIT : thanks BG... correction made with bold part