Homework SourseThere are 10 AAA batteries in a box and three are defective
Solution
Note: Let me go into detail as to the answers, because I want you to understand this stuff in case you see it again on the exam, but asked in a different way. :)
Answer: 1/15
----------------
Solutions/Discussion:
When you say the word \"and\", you typically multiply probabilities.
When you say \"or\", you typically add probabilities.
What is the probability that NONE are defective?
good and good
7/10 x 6/9
= 42/90
= 7/15
* You must decrease the numerator and denominator by 1 since you are NOT replacing the 1st battery.
* If you were sampling WITH replacement, the probability would be: 3/10 x 3/10 = 6/100.
What is the probability that EXACTLY one is defective?
good and bad or bad and good
7/10 x 3/9 + 3/10 x 7/9
= 21/90 + 21/90
= 42/90
= 7/15
What is the probability that BOTH are defective?
defective and defective
3/10 x 2/9
= 6/90
= 1/15
----------------
I hope this helped. If you have any questions, please ask them in the comment section. :)
