Question 374065
a)
There is a 0.5 probability that Box 1 is selected: 100/1000 * 99/999 = .00991
There is a 0.5 probability that Box 2 is selected: 100/2000 * 99/1999 = .00248
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b)
.00991/(.00991+.00248)
=.00991/.01239 (rounding error)
=.800 the probability that they came from box 1.
.
Ed