The fraction of a defective item getting by both inspectors is
= 
Step-by-step explanation:
Step 1; Assume that the probability of the first inspector missing a defective part is P(A) and the probability of the second inspector missing those that do get past the first inspector is P(B).
Step 2; It is given that P(A) = 0.1, we convert this into a fraction so that the final probability will be a fraction and not a decimal.
P(A) = 0.1 =
.
It is given that the second inspector misses 5 out of 10 that get past the first inspector, so P(B) =
.
Step 3; To calculate the probability of both inspectors missing a defective part, we multiply both the probabilities.
P(A and B happening) = P(A) × P(B) =
×
=
=
= 0.05%. So there is a 0.05% chance of both inspectors missing a defective part.
Simply it as follows:
1 + 39 = 40
2 + 38 = 40 etc
18 + 22 = 40
19 + 21 = 40
There are 19 of these plus 40 itself . . .therefore 20 of them
20 x 40 = 800
And finally the last number not used, 20
Therefore 800 + 20 = 820
7: the answer is C because 3/4 divided by 2/3 equals 1 1/8 and C if you multiply 3/4 x 3/2 it equals 1 1/8
14: the answer is 18 because if you add all the numbers they picked you’ll get 6 then divide it by 1/3 you’ll get 18
Then the other 2 km not sure I’m sorry