- #1

- 40

- 1

Attempted solution:

P(exactly 2 digits same) = (26

^{3}*9)/(26

^{3}*9

^{2}) = 1/9

P(exactly 2 letters same) = (26*25*3*9

^{2})/(26

^{3}*9

^{2}) = 75/676

P(2 digits same AND 2 letters same) = (26*25*3*9)/(26

^{3}*9

^{2}) = 25/2028

Required probability = 1/9 + 75/676 - 25/2028 = 0.210

But the correct answer is 0.197. Can I ask where did I go wrong? I can't figure it out...

Thanks!