Suppose that the amount of time that students spend studying in the library in one sitting is normally distributed with mean 45 minutes and standard deviation 20 minutes. A researcher observed 50 students who entered the library to study. Round all answers to 4 decimal places where possible. a. What is the distribution of X? X - N( b. What is the distribution of ¤? ¤ ~ N( c. What is the distribution of x? N

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Suppose that the amount of time that students spend studying in the library in one sitting is normally distributed with mean 45 minutes and standard deviation 20 minutes. A researcher observed 50 students who entered the library to study. Round all answers to 4 decimal places where possible.

Suppose that the amount of time that students spend studying in the library in one sitting is normally
distributed with mean 45 minutes and standard deviation 20 minutes. A researcher observed 50 students
who entered the library to study. Round all answers to 4 decimal places where possible.
a. What is the distribution of X? X - N(
b. What is the distribution of I? ã - N(
c. What is the distribution of > x? )
d. If one randomly selected student is timed, find the probability that this student's time will be
between 44 and 46 minutes.
e. For the 50 students, find the probability that their average time studying is between 44 and 46
minutes.
f. Find the probability that the randomly selected 50 students will have a total study time more than
2400 minutes.
g. For part e) and f), is the assumption of normal necessary? O NoO Yes
h. The top 20% of the total study time for groups of 50 students will be given a sticker that says "Great
dedication". What is the least total time that a group can study and still receive a sticker?
minutes
Transcribed Image Text:Suppose that the amount of time that students spend studying in the library in one sitting is normally distributed with mean 45 minutes and standard deviation 20 minutes. A researcher observed 50 students who entered the library to study. Round all answers to 4 decimal places where possible. a. What is the distribution of X? X - N( b. What is the distribution of I? ã - N( c. What is the distribution of > x? ) d. If one randomly selected student is timed, find the probability that this student's time will be between 44 and 46 minutes. e. For the 50 students, find the probability that their average time studying is between 44 and 46 minutes. f. Find the probability that the randomly selected 50 students will have a total study time more than 2400 minutes. g. For part e) and f), is the assumption of normal necessary? O NoO Yes h. The top 20% of the total study time for groups of 50 students will be given a sticker that says "Great dedication". What is the least total time that a group can study and still receive a sticker? minutes
Expert Solution
Step 1

The normal distribution is the most useful theoretical distribution for continuous variables. For the normal distribution,

mean=μ, S.D=σ, symbolically we write,

X~N(μ,σ).

The normal curve is always bell-shaped curve.

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