MartinMag, can you explain it using probability, please? thanks!
Suppose we have colors: A,B,C,D and E
Prob of getting 1 shoe of color A=2/10=1/5
After we got the A shoe we have 9 shoes left, then the prob of getting the other A shoe is 1/9
So, probability of getting 2 shoes of color A is 1/5*1/9
Since we have 5 pairs of different colors, the answer is 1/5*1/9*5
Hope it helps!
Here is another way of thinking about this probabilisticly.
Whatever color you pick for the first shoe, there is only one shoe out of the remaining 9 that match it, hence, the probability is 1/9.
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993