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Answer
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P(x<1) = 0.841345

↓Steps Explained:↓

Given X = 125, μ = 105, and σ = 20

Calculate P(X < Z)

Z-score formula

Using the Normal Distribution, Calculate P(X < 125)

Z  =  X - μ
  σ/√1

Z  =  125 - 105
  20/√1

Z  =  20
  20/1

Z  =  20
  20

Z = 1

From the table below, we see that our Z value is = 0.341345

Z-table Lookup Value

The z-table probability runs from 0 to z and -z to 0

Z value = 0.341345

Since that represents ½ of the graph, we add 0.5 to our value → 0.5 + 0.341345

P(x<1) = 0.841345

Final Answer

P(x<1) = 0.841345
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Related Calculators:  Negative Binomial Distribution  |  Geometric Distribution  |  Binomial Distribution