MathRevolution wrote:
There are 5 apples in a bag. 4 apples are good but 1 apple is rotten. If you take out 2 apples from the bag, what is the probability that 1 apple selected is rotten?
A. \(\frac{1}{3}\)
B. \(\frac{1}{4}\)
C. \(\frac{2}{5}\)
D. \(\frac{3}{5}\)
E. \(\frac{1}{7}\)
The number of ways to select 2 apples consisting of 1 good apple and 1 rotten apple is selected is 4C1 x 1C1 = 4 x 1 = 4.
The number of ways to select 2 apples from 5 is 5C2 = (5 x 4)/2! = 10.
So the probability is 4/10 = 2/5.
Alternate Solution:
There are two ways to get 1 good and 1 bad apple in this scenario: GB or BG
The probability of GB is 4/5 x 1/4 = 1/5
The probability of BG is 1/5 x 4/4 = 1/5
Since either outcome satisfies the requirement, we add the two probabilities, obtaining 1/5 + 1/5 = 2/5.
Answer: C
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