Answer :
The probability that we are lucky and find both of the defective fuses in the first two tests with replacement is 1/13 and without replacement is 12/169.
In the given question, 9 good fuses and 4 defective ones have been mixed up.
To find the defective fuses, we test them one-by-one, at random.
We have to find the probability that we are lucky and find both of the defective fuses in the first two tests.
1). with replacement
2). without replacement
There are 9 good fuses and 4 defective ones.
So the total number of defective fuses = 9+4 = 13
Now the probability first test will find a defective is 4/13
Without replacement, 2nd will find another defective with probability = 3/12.
Probability of finding 2 defectives on 1st two tests is
P(R) = 4/13 x 3/12
P(R) = 12/156
P(R) = 1/13
Now the with replacement the probability is
P(E) = 4/13 x 3/13
P(E) = 12/169
The probability that we are lucky and find both of the defective fuses in the first two tests with replacement is 1/13 and without replacement is 12/169.
To learn more about probability link is here
brainly.com/question/11034287
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