Three sigma rule

The height of trees in a given stand is known to be a quantity with a normal probability distribution with a mean value of 15 m and a variance of 5 m2. Determine the interval in which there will be tree heights in such a stand with a probability of 90%

Correct answer:

x1 =  11.334
x2 =  18.666

Step-by-step explanation:

m=15 m σ=5=5 m2.2361 m p=90%=90100=0.9  s=3.666  x1=ms=153.666=11.334

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