Question 286302
Researchers have created any index they claim measures an adult male's propensity to commit an act of road rage.
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This index is calculated from the answers to a questionairre and the scores are normally distibuted amoung US adult males, with a mean of 100 and a standard deviation of 30.
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Researchers assess a group of twenty adult male drivers convicted of committing road rage. The mean score for the group is 50.8.
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What percentage of US adult males would be expected to obtain a score equal to or less than that of road-ragers?
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x = zs+u
50.8 = z*30 + 100
30z = -49.2
z = -49.2/30 = -1.64
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P(x <= 50.8) = P(z <= -1.64) = normalcdf(-100,-1.64) = 0.0505 = 5.05%
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Cheers,
Stan H.