I believe you're saying the same thing as huda.

For example, I believe you're both saying G1 and G2 are indistinguishable (identical). The same applies to R1 and R2

_ _ _ _

Experiment1: Choose a G for the first slot
Experiment2: Choose an R for the last slot
Experiment3: Choose a letter from the remaining for the third slot
Experiment4: Choose a letter from the remaining for the fourth slot

We have 2 G's and 2 R's

Total Outcome in Experiment1: 2
Total Outcome in Experiment2: 2
Total Outcome in Experiment3: 8
Total Outcome in Experiment4: 7

We use principle of counting

Total outcomes= 2*2*8*7

But we need to divide by (2*2), because we can't distinguish the two G's or R's if the words contain two of them.

Total outcomes= (2*2*8*7)/(2*2)= 8*7

8P2= 8!/(8-2)!= 8!/6!= 8*7

Final Answer: A

A way to do it is:

G _ _ R

With 1 G and 1 R already used, you have one of the 8 letters that can fill the first blank and one of 7 letters can fill the second blank.

So, G 8 7 R. So you can arrange the letters in 8*7 ways.

8P2 = 8*7 = 56.

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