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The weights of grapefruits in a bin are normally distributed with a mean of 261 grams and a standard deviation of 9.4 grams. 

Approximately 20% of the grape fruits weight less than which amount?

 

239

247

253

261

 Apr 4, 2019
 #1
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You need to find the z-score which is closest to .2000 (20%)

  Look at your negative z-score table

 

   Look at  z= -.84

 

 So -.84 standard deviations below the mean represents 20%       261  - .84 X (9.4) = 253.1 gms

 Apr 4, 2019

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