This Question: 1 pt This Test: 13 hours and a standard deviation of 1.1 hours A

Question

This Question: 1 pt This Test: 13 hours and a standard deviation of 1.1 hours A student is randomly selected Find the folowing probabilities The times per week a student uses a lab computer are noemally distributed, with a mean of 66 (a) Find the probablity s at be student uses a lab computer less than 4 hours per week that the student uses a lab computer more than 9 hours per week Find the probability that the student uses a lab computer (c) Find the Round to three decimal places as needed ) b) The probability that a student uses a lab computer belween 6 and 8 hours per week is Round to three decimalplaces as needed) (c) Theprobabity that a student uses a lab computer more than 9 hours per week is Round to theee decimal places ais needed) e Type here 2 3 6 8

Explanation / Answer

A) P(x < 4) = P((x - mean)/SD < (4 - mean)/SD)

= P(Z < (4 - 6.6)/1.1)

= P(Z < -2.36)

= 0.0091

B) P(6 < x < 8)= P((6 - mean)/SD < (x - mean)/SD < (8 - mean)/SD)

= P((6 - 6.6)/1.1 < Z < (8 - 6.6)/1.1)

= P(-0.55 < Z < 1.27)

= P(Z < 1.27) - P(Z < -0.55)

= 0.8980 - 0.2912

= 0.6068

C) P(x > 9) =  P((x - mean)/SD > (9 - mean)/SD)

= P(Z > (9 - 6.6)/1.1)

= P(Z > 2.18)

= 1 - P(Z < 2.18)

= 1 - 0.9854 = 0.0146

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