A family of 4 brothers and 3 sisters is to be arranged in a row, for a photograph. In how many ways can they be seated if all the sisters not together ?	Choices:
A) 4270
B) 4820
C) 4320
D) 4620
E) 4520
Since the 3 sisters are inseperable, consider them as one single unit. This together with the 4 brothers make 5 persons who can be arranged among themselves in 5! ways. In everone of these permutations, the 3 sisters can be rearranged among themselves in 3!. Hence the total number of arrangement required = 5!x 3! =120x6=720. The number of arrangements of all the 7 persons without any restriction =7!= 5040 Number arrangement required =5040-720= 
<gadget id="calculator">5040-720</gadget>
<output>4_320</output>
4320. Answer : 4320
<result>C</result>
A family of 4 brothers and 3 sisters is to be arranged in a row, for a photograph. In how many ways can they be seated if all the sisters not together ?