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14 September, 13:02

The scores on an exam are normally distributed, with a mean of 75 and a standard deviation of 5. What percent of the scores are less than 80?

A. 50%

B. 84%

C. 13.5%

D. 16%

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Answers (1)
  1. 14 September, 13:09
    0
    B. 84%

    Step-by-step explanation:

    Given

    Mean = π=75

    Standard Deviation = σ=5

    As we have to calculate the percentage of score less than 80, we will find the z-score of 80

    z = (x-μ) / σ

    = (80-75) / 5

    =5/5

    =1

    The z-score table value for 1 is 0.8413.

    For converting this value into percentage, the value will be multiplied by 100.

    So,

    Percentage of students whose score is less than 80 = 0.8413*100

    =84.13%

    Rounding off gives us : 84%

    So option B is the correct answer ...
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