The time to complete an exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the 68-95-99.7

Question

The time to complete an exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the 68-95-99.7 rule, what percentage of students will complete the exam in less than 60 minutes

in progress 0
Iris 2 weeks 2021-09-11T22:10:15+00:00 1 Answer 0

Answers ( )

    0
    2021-09-11T22:11:24+00:00

    Answer:

    16% of students will complete the exam in less than 60 minutes

    Step-by-step explanation:

    The Empirical Rule(68-95-99.7) states that, for a normally distributed random variable:

    68% of the measures are within 1 standard deviation of the mean.

    95% of the measures are within 2 standard deviation of the mean.

    99.7% of the measures are within 3 standard deviations of the mean.

    In this problem, we have that:

    Mean = 70

    Standard deviation = 10

    What percentage of students will complete the exam in less than 60 minutes

    60 = 70-10

    So 60 is one standard deviation below the mean

    By the Empirical Rule, 68% of the measures are within 1 standard deviation of the mean, that is, from 60 to 80 minutes. The other 100-68 = 32% is outside this interval. Since the normal distribution is symmetric, 16% of those are below 60 and 16% of those are above 80.

    16% of students will complete the exam in less than 60 minutes

Leave an answer

45:7+7-4:2-5:5*4+35:2 =? ( )