If it takes Daniel 9 hours to clean an office building and it takes Mark 6 hours, how long would it take the two of them, workin
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Answer:
8/33 = 0.242
Step-by-step explanation:
There are 12 socks to begin with and one is taken;
The second is picked from the remaining 11 and will either match the first or not;
The probability of matching is 1/11 and 10/11 for not matching;
If the sock matches, no further sock is taken;
If the socks don't match, a 3rd sock is taken;
The 3rd sock is taken from the remaining 10, 1 of which will match with the first sock and another which will match the second;
Therefore, the probability of taking a matching sock on the third pick will by 2/10 or 1/5 and the probability it will not match either of the first two is 8/10 or 4/5;
Once again, if the sock matches either of those previously taken, no further sock is taken;
If the socks don't match, a 4th sock is taken;
Now, there are 9 socks remaining in the drawer;
Picking is repeated;
The process is logical;
The attached picture shows a tree diagram representing this information in an easily digestible way and makes it easy to work out the desired probability;
With tree, diagrams, you just multiply across until you get to your desired outcome;
In this case, we are finding the probability of picking 5 socks exactly;
Each process splitting represents the picking of a sock;
The probability will be:
10/11 × 8/10 × 6/9 × 4/8 = 8/33 = 0.242...
