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The scores of students on the logic test of an entrance examination are normally distributed
with a mean of 500 and a standard deviation of 100. Find the following test score probabilities.
(a) What is the probability a student scores over 400?
(b) What is the probability a student scores over 650?
(c) What is the probability a student scores under 375?
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Each normal curve is a bell-shaped curve.
In this problem, the probabilities are the areas under the described/specified normal curve on the left or on the right of the assigned raw marks.
These probabilities can be found using the standard function normalcdf.
normalcdf stands for normal cumulative distribution function.
Its format is normalcdf(z1,z2,m,SD), where z1, z2 are the raw marks, m is the mean value, SD is the standard deviation value.
You may use this function on your calculator.
(a) P = normalcdf(400,9999,500,100).
(b) P = normalcdf(650,9999,500,100).
(c) P = normalcdf(-999,375,500,100).
If everything is clear to you from my explanations, then boldly go forward,
get the values and complete the assignment on your own.
You also can use an online free of charge calculator at this site
https://onlinestatbook.com/2/calculators/normal_dist.html
The calculator has perfect description, instructions and design, along with clear graphical output, so EVERY person,
including beginners, may work with it on his or her own, even having minimum knowledge on the subject.
I always recommend to beginner students to start using this calculator.
When you get enough practice and understanding, you may switch back to regular calculators.