How many different signals can be transmitted by hoisting 3 red, 4 yel

Question

How many different signals can be transmitted by hoisting 3 red, 4 yellow and 2 blue flags on a pole, assuming that in transmitting a signal all nine flags are to be used?

A. 1260
B. 1080
C. 960
D. 880
E. 720

imeanup · Answer

\frac{9!}{3!*4!*2!}=9*4*7*5=1260

Ans A

mehro023 · Answer

since all 9 flags need to be used in order to produce a signal, the flags could be used in many ways.

RRRBBYYYY
RBBYYRYYR
.
.
.
.
.
.
and so on,

Thus, the number of ways is: 9!/(2!*3!*4!) = 1260 = A

Please let me know if you have questions

Kudos if you like my solution

unraveled · Answer

R_1 = R_2 = R_3 = R 
 Y_1 = Y_2 = Y_3 = Y_4 = Y 
 B_1 = B_2 = B

In reality there are 9! ways to arrange the different signals but since every red color flag would give a same signal. Hence position of any one of the 3 red flags would be same as to be held by 2nd or 3rd red flag. 
This would be same for yellow as well as blue flag.

Hence unique ways of arrangements of flags =  \frac{9!}{3!*4!*2!} = 1260

Answer A.

How many different signals can be transmitted by hoisting 3 red, 4 yel

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How many different signals can be transmitted by hoisting 3 red, 4 yel

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