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D
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Difficulty:
75%
(hard)
Question Stats:
49% (02:34) correct
51%
(02:47)
wrong
based on 37
sessions
History
Date
Time
Result
Not Attempted Yet
A manufacturer produced a batch of electronic chips, 40 percent of which are defective. A test has been devised to detect defective chips. The test correctly identifies 90 percent of defective chips and 80 percent of non defective chips. If the test indicates that a randomly selected chip from the batch is defective, what is the probability that the chip is actually non-defective?
(A) 1/20
(B) 1/10
(C) 1/5
(D) 1/4
(E) 1/3
(A) 1/20
(B) 1/10
(C) 1/5
(D) 1/4
(E) 1/3
06 Mar 2026, 01:24
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kevincan
Let’s assume the total chips to be 100x.
Defective chips = 40%*(100x) = 40x
Non defective chips = 60x
We run the test, correctly identifies defective chips 90% time.
Among the defective chips of 40x.
Defective found correct = 90%*40x = 36x
Defective but not found = 4x.
Among the non defective chips of 60x. Test identifies 80% of non defective chips.
Non defective found correct = 80%*(60x) = 48x
Non defective but not found correct = 12x.
Total defective
= Defective found correctly + Non defective wrongly termed as defective.
= 36x + 12x
= 48x
Probability the chip is non defective = 12x/48x
= 1/4
Option D.
