Math Destroyer 2015 test 2 #35

[Hard Work Pays Off]

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So the question asks : a bag contains 7 walnuts, 4 cashews, and 3 pistachio nuts..etc. it asks about the probability of getting one cashew and one walnut. the answer is 4/13 and I kind of know how to get there but there is another answer choice which is 28/91 and that value equals 4/13. like it is the same value, so why is the answer 4/13, if they both equal 0.30769231 ?

 

[Charles_Darwin]

So the question asks : a bag contains 7 walnuts, 4 cashews, and 3 pistachio nuts..etc. it asks about the probability of getting one cashew and one walnut. the answer is 4/13 and I kind of know how to get there but there is another answer choice which is 28/91 and that value equals 4/13. like it is the same value, so why is the answer 4/13, if they both equal 0.30769231 ?

I'm not Nancy so I can't say for sure, but I think that's an error. I've got the 2016 math destroyer on me and the answer choice is 4/13 or 27/91, not 28

 

[DAT Destroyer]

So the question asks : a bag contains 7 walnuts, 4 cashews, and 3 pistachio nuts..etc. it asks about the probability of getting one cashew and one walnut. the answer is 4/13 and I kind of know how to get there but there is another answer choice which is 28/91 and that value equals 4/13. like it is the same value, so why is the answer 4/13, if they both equal 0.30769231 ?

It has been corrected in the 2016 edition.
4/14)*(7/13)= 2/13
We then multiply the answer by 2 to get 4/13.
The reason we multiply by 2 is because there are 2 ways to get a walnut and a cashew : a walnut then a cashew or a cashew then a walnut.
If the question specifies that the first one is a cashew and a second one is a walnut then the answer is 2/13