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## In a statistics mid-term exam graded out of 100 points, the distribution of the exam scores was bi-modal with a mean of 70 points with a sta

Question

In a statistics mid-term exam graded out of 100 points, the distribution of the exam scores was bi-modal with a mean of 70 points with a standard deviation of 10 points. What percentage of students scored between 40 points and 100 points?

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2021-09-12T07:51:41+00:00
2021-09-12T07:51:41+00:00 2 Answers
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## Answers ( )

Answer:

Step-by-step explanation:

Assuming a normal distribution for the distribution of the points scored by students in the exam, the formula for normal distribution is expressed as

z = (x – u)/s

Where

x = points scored by students

u = mean score

s = standard deviation

From the information given,

u = 70 points

s = 10.

We want to find the probability of students scored between 40 points and 100 points. It is expressed as

P(40 lesser than x lesser than or equal to 100)

For x = 40,

z = (40 – 70)/10 =-3.0

Looking at the normal distribution table, the corresponding z score is 0.0135

For x = 100,

z = (100 – 70)/10 =3.0

Looking at the normal distribution table, the corresponding z score is 0.99865

P(40 lesser than x lesser than or equal to 100) = 0.99865 – 0.0135 = 0.98515

The percentage of students scored between 40 points and 100 points will be 0.986 × 100 = 98.4%

Step-by-step explanation:At least 89%

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