Computers and Technology, 10.04.2020 16:52, shikiaanthony
A scientist measures performance on a PVT (psychomotor vigilance task) in which the subject is supposed to push a button each time a light appears on the screen. The number of times the subject misses is a good measure of sleepiness. Twelve subjects perform this task and have lapses of 1, 1, 5, 3, 10, 2, 5, 5, 8, 2, 5, 1, respectively. a) Fill in the frequency table: b) In the graph to the right, draw the histogram of this data. Label the data carefully. c) The data was taken in the morning after the subjects had gotten 8 hours of sleep. The average number of lapses was 4 and the standard deviation of the data was 2.77. What percentage of the data falls in the SD error bars? (Actually calculate it. Show your work.) Does this agree with rule of thumb of 68% if the data is normally distributed? Why or why not?
Answers: 2
Computers and Technology, 23.06.2019 10:20, chonawilson4
Suppose there is a relation r(a, b, c) with a b+-tree index with search keys (a, b).1. what is the worst-case cost of finding records satisfying 10 < a < 50 using this index, in terms of the number of records n1, retrieved and the height h of the tree? 2. what is the worst-case cost of finding records satisfying 10 < a < 50 and 5 < b < 10 using this index, in terms of the number of records n2 that satisfy this selection, as well as n1 and h defined above? 3. under what conditions on n1 and n2, would the index be an efficient way of finding records satisfying the condition from part (2)?
Answers: 1
Computers and Technology, 24.06.2019 17:40, hughesnatalia2003
File i/o activity objective: the objective of this activity is to practice working with text files in c#. for this activity, you may do all code in the main class. instructions: create an app that will read integers from an input file name numbers. txt that will consist of one integer per record. example: 4 8 25 101 determine which numbers are even and which are odd. write the even numbers to a file named even. txt and the odd numbers to a file named odd. txt.
Answers: 3
A scientist measures performance on a PVT (psychomotor vigilance task) in which the subject is suppo...
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