# Probability Question Help

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• #47204

Schuette
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A Standardized test has a mean of 90 with a standard deviation of 5.
1. If you had a score of 95 on a standard test. What is the probability of observing a score of 95 on this test?

2. Another individual had scored 100 on the same test. What is the probability of an individual obtaining a score between 95 and 100?

3. What is the probability of an individual failing this text, given that any score below a Z= -3 would fail?

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#157164

Psycho
Participant

It looks like you’re taking an introductory course to psychology. I won’t give you the answer but some hints.
Mean = 95, standard deviation = 5, score = 95, look up the z-value at 1.67.
Score between 95 and 100 is the difference between the cumulative probability at 1.96 (100 score) and 1.67 (95 score), i.e. the difference between 1 and 2 standard deviations above the mean.
Look up the cumulative distribution at the z-value of -3, that will give you that answer.

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#157299

Van Loon
Participant

If it is continous data, you cant give the probalility for
exact the number 95, can you ?
Jan

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