Computer Programming Concepts and Visual Basic David I. Schneider

210 Computer Programming Concepts and Visual Basic
FIGURE 6-13 Possible Outcome of Project 1
2. Statisticians use the concepts of mean and standard deviation to describe a
collection of data. The mean is the average value of the items, and the standard
deviation measures the spread or dispersal of the numbers about the mean. Formally,
if x1, x2, x3, . . . , xn is a collection of data, then
mean = m =
(x1 standard deviation = s =
– m)
Write a computer program to
(a) Place the exam scores 59, 60, 65, 75, 56, 90, 66, 62, 98, 72, 95, 71, 63, 77,
65, 77, 65, 50, 85, and 62 into an array.
(b) Calculate the mean and standard deviation of the exam scores.
(c) Assign letter grades to each exam score, ES, as follows:
ES ≥ m + 1.5s A
m + .5s ≤ ES < m + 1.5s B
m – .5s ≤ ES < m + .5s C
m – 1.5s ≤ ES < m – .5s D
ES < m – 1.5s F
For instance, if m were 70 and s were 12, then grades of 88 or above would
receive A’s, grades between 76 and 87 would receive B’s, and so on. A
process of this type is referred to as curving grades.
(d) Display a list of the exam scores along with their corresponding grades as
shown in Figure 6-14.
2 + (x2 – m) 2 + (x3 – m) 2 + . . . + (xn – m) 2
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n – 1
FIGURE 6-14 Output of Project 2
x1 + x2 + x3 + . . . + xn
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n
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