chaiCoder's blog

By chaiCoder, history, 11 years ago, In English

Hi,

New to CF. Hello!

I have some math trouble with the following. Please help me. It seems too simple, but I'm kinda stuck on it for quite sometime now..

Let's say I'm a shopkeeper. I have 1000 apples with me (some are rotten), out of these I sold 700 apples today, meaning I sold 70% of the apples I have. Out of these 700, 210 apples were rotten (gone bad)(which is 30%). I need to know proportionately the number of good apples I had in the beginning (in place of 1000).

Please help. I can't seem to get my head around it.

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11 years ago, hide # |
 
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The data in the question seems inadequate. There is no information on the proportion of good and rotten apples in the 300 apples (the first 30%) that were not sold. There is also no relation between any other value and these 300 apples. So incomplete info. Better leave it !

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    11 years ago, hide # ^ |
     
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    Hey, we can assume that other 30% was all good.

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      11 years ago, hide # ^ |
       
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      I still dont know if i understood question correctly but

      out of 70% , 30% were bad that means 0.7*0.3=0.21; 1-0.21=0.79 so that means 79% of all apples are good.

      Alternatively just substract bad apples from 1000 and find percentage. 1000-210=790, good apples = 790/1000=79%

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11 years ago, hide # |
 
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You didn't phrase the question well-enough. In case there are only 210 rotten apples then obviously you have 790 good ones and therefore 79% good ones.

However as in a real situation a random percentage will be rotten, and assuming the customers can't predict which ones are, they'll choose each with the same probability, so in the long run (1000 apples seems like a long run enough for a good estimate) the percentage of rotten apples sold and rotten apples in total will be the same. So in that case 30% of the apples were rotten and we had 70% good ones.

However in the vague way you phrased the question the information is insufficient.