The average age of a breed of dog is 19.4 years. If the distribution of their ages is normal and
20% of dogs are older than 22.8 years, find the standard deviation
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1
Answer:
4
Step-by-step explanation:
If 20% of dogs are older than 22.8 years, then 22.8 must be the 80th percentile.
The z-score for 80th percentile is z=0.842
To solve for the standard deviation,
(22.8-19.4) / (standard deviation) = 0.85
standard deviation = 3.4/0.842 = 4
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