Anonymous asked in Science & MathematicsMathematics · 4 weeks ago

The lengths of lumber a machine cuts are normally distributed with a mean of 105 inches and a standard deviation of 0.7 inch ?

(a) What is the probability that a randomly selected board cut by the machine has a length greater than 105.21 inches? 

b) A sample of 38 boards is randomly selectedWhat is the probability that their mean length is greater than 105.21 Inches?

(A) Probability is- 

(B) Probability is- 

1 Answer

  • rotchm
    Lv 7
    4 weeks ago

    Hints: a) Convert 105.21 to z space via z=(x-avg)/std. Then lookup in your z table.

    b) For a sample of n, the avg remains the same. The sd becomes [left for you]. 

    Unanon yourself and we will detail further if need be.

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