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If the weight (in grams) of cereal in a box of Lucky Charms is N(489,6), what is

ID: 3134748 • Letter: I

Question

If the weight (in grams) of cereal in a box of Lucky Charms is N(489,6), what is the probability that the box will contain less than the advertised weight of 464 gm? Note: You may need to use Excel to calculate the exact probabilities. (Round your answer to 5 decimal places.)
If the weight (in grams) of cereal in a box of Lucky Charms is N(489,6), what is the probability that the box will contain less than the advertised weight of 464 gm? Note: You may need to use Excel to calculate the exact probabilities. (Round your answer to 5 decimal places.)

Explanation / Answer

We first get the z score for the critical value. As z = (x - u) / s, then as          
          
x = critical value =    464      
u = mean =    489      
          
s = standard deviation =    6      
          
Thus,          
          
z = (x - u) / s =    -4.166666667      
          
Thus, using a table/technology, the left tailed area of this is          
          
P(z <   -4.166666667   ) =    1.54543*10^-5 or 0.0000154543 [ANSWER]

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[You can use =NORMDIST(464, 489, 6, 1) to produce this.]