vikasp99 wrote:
A restaurant is hanging 7 large tiles on its wall in a single row. How many arrangements of tiles are possible if there are 3 white tiles and 4 blue tiles?
A. 35
B. 12
C. 21
D. 84
E. 28
Hi..
Total ways these 7 tiles can be arranged =7!
However these contain duplicity as 3 tiles are of one colour and other 4 are of other colour..
So eliminating these = \(\frac{7!}{3!4!}\)=35
A
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1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
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82% (01:10) correct 
