Solution:
The required number of ways
= the number of ways in which 8 girls can sit in a row – the number of ways in which two sisters sit together
.
In a group of 8 girls, two girls are sisters. The number of ways in which the girls can sit in a row so that two sisters are not sitting together is
In a group of 8 girls, two girls are sisters. The number of ways in which the girls can sit in a row so that two sisters are not sitting together is
