SOLUTION: The weight of a small Starbucks coffee is a normally distributed random variable with a mean of 315 grams and a standard deviation of 16 grams. Find the weight that corresponds to

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Question 1197070: The weight of a small Starbucks coffee is a normally distributed random variable with a mean of 315 grams and a standard deviation of 16 grams. Find the weight that corresponds to each event. (Round your final answer to 2 decimal places.)
a)Highest 20 percent_____
b)Middle 60 percent____ to ____
c)Highest 80 percent____
d)Lowest 15 percent____
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi  
Recommend the use of a calculator and understanding of the  standard normal curve 

Normal Distribution:  µ = 0 and σ = 1
z score represents the area under the curve to the LEFT of its value

Using TI or similarly an inexpensive calculator like an Casio fx-115 ES plus
Calculator function Invnorm(X) gives value to the LEFT of z

Highest 20 percent |z= Invnorm(80%) = .84 (to 2 decimal places)
|blue%2816%29%2A.84+%2B+315+=+blue+%28328.44%29 weight > 328.44

Middle 60%    |z= Invnorm(20%) = -.84 (to 2 decimal places)
Middle 60%:   -.84 to .84
|blue%2816%29%2A%28-.84%29+%2B+315+=+blue+%28314.46%29 
|blue%2816%29%2A.84+%2B+315+=+blue+%28328.44%29 
weight from:  314.46 to 328.44  lbs

Highest 80 percent:   > 314.26 lbs


Lowest 15 percent:   |z= Invnorm(15%) = -1.04  |blue%2816%29%2A%28-1.04%29+%2B+315+=+blue+%28298.36%29  weight ≤ 298.36 lbs
  
Wish You the Best in your Studies.