SOLUTION: A mechanic working under a car requires three different size wrenches from her toolbox, which contains nine different wrenches. Reaching for her toolbox, she grabs three of them at

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Question 1192982: A mechanic working under a car requires three different size wrenches from her toolbox, which contains nine different wrenches. Reaching for her toolbox, she grabs three of them at random. What is the probability that the mechanic has all of the wrenches she needs?
Answer by ikleyn(52855) About Me  (Show Source):
You can put this solution on YOUR website!
.

She needs exactly one triple of total possible   C%5B9%5D%5E3 = %289%2A8%2A7%29%2F%281%2A2%2A3%29 = 84   different triples.


So the probability to guess the triple randomly is   1%2F84.             ANSWER


Solved and explained.

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This problem is on  COMBINATIONS.

On  Combinations,  see introductory lessons
    - Introduction to Combinations
    - PROOF of the formula on the number of Combinations
    - Problems on Combinations
in this site.

Also,  you have this free of charge online textbook in ALGEBRA-II in this site
    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this online textbook under the topic  "Combinatorics: Combinations and permutations".


Save the link to this textbook together with its description

Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson

into your archive and use when it is needed.