P[2 ones]= 1/36
P[1 one]= 10/36]
P[0 ones]=25/36
0 ones and box contains 10 red,0 white chips. probability of choosing red chip =10/10 [you will see why written as 10/10 and not 1]
1 ones box contains 7 red ,3 white ,probability of choosing red chip= 7/10
2 ones box contains 4 red and 6 white , probability of choosing red =4/10
P[0] and choosing red = 25/36 x 10/10= 250/360
P[1] and choosing red = 10/36 x 7/10= 70/360
P[2] aqnd choosing red = 1/36 x 4/10= 4/360
knowing we have a red chip, 250 out of [250+70+4] is probability of 0 ones. 250/324
knowing we have a red chip,70 out of 324 is probability of 1 one
knowing we have a red chip, 4 out of 324 is probability we had 2 ones
Please check for errors
Arthur
