Suppose that a student who is about to take a multiple choice test has only learned 40% of the material covered by the exam. Thu
1 answer:
Answer:
There is a 52% probability that she will get it right.
Step-by-step explanation:
We have these following probabilities:
A 40% probability that the student knows the answer to a question.
A 60% probability that the student does not know the answer to a question.
If the student does not know the answer to a question, a 20% probability of getting the question right guessing.
If we choose a question at random from the exam, what is the probability that she will get it right?
40% probability that she knows the answer
60% that she has to guess, when there is a 20% probability of getting it right. So
There is a 52% probability that she will get it right.
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Answer:
a) 8.2962
b) 6.3956
c) 3.845
Step-by-step explanation:
Z-score:
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:
(a) What response represents the 85th percentile?
This is X when Z has a pvalue of 0.85. So X when Z = 1.037.
(b) What response represents the 62nd percentile?
This is X when Z has a pvalue of 0.62. So X when Z = 0.306.
(c) What response represents the first quartile?
The first quartile is the 100/4 = 25th percentile. So this is X when Z has a pvalue of 0.25, so X when Z = -0.675.