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Student Name
Part 2 Calculation question (30 points).
Instructions: You need show your steps. You will receive only half the points if only final
number is provided (when it is correct). You will receive 0 points when only final number is
provided (and when it is incorrect). Also, keep 2 decimal places when you need to round
numbers.
1. There are only four students in total from your class, and everyoneàIQ scores are: 102,109, 110,
and 120 respectively. You goal here is to understand and describe the IQ scores from your class.
Question: calculate and report the variance and standard deviation for these scores. (8 points).
Tips: is this a sample or a population?
2. A health scientist gathered data on how many times a year a group of elementary students got
sick. Frequency counts for data from 65 students has been started below. First, finish this chart
by calculating the cumulative frequency. Next, find the mean (in other words, how many times
per year the students got sick on average?). (7 points)
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Frequency (f)
6 times
2
5 times
5
4 times
13
3 times
20
2 times
15
1 time
7
0 times
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Cumulative Frequency (fc)
3. If random samples, each with n= 100 scores, are selected from a normal population with ?=
100 and ? = 10,
1) Calculate the standard error of the mean. 2) What kind of information does the standard error
of the mean give you? In other words, how do we interpret the value of standard error of the
mean here? (7 points)
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4. The population of IQ scores forms a normal distribution with a mean of ?= 100 and ?
= 15. What proportion of the population consists of individuals with IQ scores higher
than 130? (8 points)

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