Answer:
0.667
Explanation:
Data provided:
x 0 1 2 3 4 5 6
P(X = x) 0.10 0.20 0.40 0.15 0.05 0.05 0.05
Now,
The probability that less than 5 items will be sold in a week given that 3 items have already been sold can be calculated as;
P ( less than 5 items sold | 3 or more items sold )
=

=
or
P ( less than 5 items sold | 3 or more items sold ) =
or
P ( less than 5 items sold | 3 or more items sold ) =
or
P ( less than 5 items sold | 3 or more items sold ) = 0.667