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., asked in Science & MathematicsMathematics · 8 years ago

Help with stats homework?

How would one solve this? Or at least attempt to?

Data collected over a long period of time show that the length of time x to complete a particular college entrance test is normally distributed with an average of 125 minutes and a standard deviation of 18 minutes. What is the probability that a student taking this test will finish in 100 minutes or less? Round your answer to 4 decimal places. Remember to round all z values to 2 decimal places.

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  • 8 years ago
    Favorite Answer

    you would need to compute the z score and then what you know about area under a normal curve to find the answer. The z score is number of standard deviations you are from the mean, so

    zscore = (value - mean)/ standard deviation = 100 - 125 = -25/18 = -1.3888... or -1.39 which is 0.1587 according to wolframalpha.com

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