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ASK THE PROFESSOR FORUM

Course Documents

Chapter 1 - Intro

Chapter 2 - Methods for Describing Sets of Data

Chapter 3 - Probability

Chapter 4 - Discrete Random Variables

Chapter 5 - Normal Random Variables

Chapter 6 - Sampling Distributions

Chapter 7 - Confidence Intervals

Chapter 8 - Tests of Hypothesis: One Sample

Chapter 9 - Confidence Intervals and Hypothesis Tests: Two Samples

Sample Exam I: Chapters 1 & 2

Sample Exam II: Chapters 3 & 4

Sample Exam III: Chapters 5 & 6

Sample Exam IV: Chapters 7 & 8

Ask the Professor Forum

in homework from chapter 2, numbers 4 and 5, when i add the relative frequency numbers up they should give me 1.00 but they give me 1.500 even though my numbers are the same as the ones in the answer that the homework gives. is that fine? because the same thing keeps happening when i do the percentages, it does not add up to 100% but instead it adds up to like 105%. i am very confused if that is fine or if it MUST come out to 1.00 and 100%.

Posted to STATS 1 on Wednesday, January 22, 2014   Replies: 2


Professor Mcguckian
01/27/2014
6:13 PM EST

Hi Maria,

Sorry to respond to this post late, but I did not see it until today. I don't know how I overlooked it.

In homework problem 4, the relative frequencies are: 0.103, 0.231, 0.385, 0.205, 0.077. If we add these up, we get 1.001. As a percent that is 100.1%. That is not exactly 100%, but remember that we have some rounding error because we are forced to round the decimals at some point. This is close enough to 100%. If we had a sum of 105% or even 101% that would indicate we made an error someplace, but if it is 99.9% or 100.1% it is close enough to assume the difference is due to rounding error. 

I hope that clears it up,

Professor McGuckian

 


.
01/28/2014
6:25 PM EST
Yeah it really helps,thank you so much! :)

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