# Spring 2013 – MAT 1272 Statistics – Reitz

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• Questions about WeBWorK, classwork, and exam reviews
• #16644

sarina
Participant

I got it finally. Thank you.

#16645

Jonas Reitz
Participant

Good job!

#16608

hi professor Reitz,

can you please give an extension on this hw assignment ive been working on it since class and I can’t figure out how to get the answer for 12 c. Of the 14 people who show up, 4 are women. How many ways are there to choose 10 players to take the field if at least one of these players must be women?

i also can’t figure out problem # 2
a financial analyst has determined that there is a 20% probability that a mutual fund will outperform the market over a 1-year period given that it outperforms the market the previous year. If only 16% of mutual funds outperform the market during any year, what is the probability that a mutual fund will outperform the market 2 years in a row?

Can you please put up the answer key to the test and maybe show how you did the step by step to get that answer?? Please can you do this ASAP because I need as much time to study for this test as i can get!!

thanks

#16646

Jonas Reitz
Participant

Dear America,

I realize this response is a little late (but I don’t usually check my email as late as 11:45, when you left your message) – sorry. While I can’t give an extension on the WeBWorK, I should point out that the two questions you mentioned (12c and 2) gave quite a few people trouble. I posted some hints and explanation about both of these questions in the above comments on this discussion thread — take a look through and you’ll see (If you’re spending a long time stuck on a problem, this is a good place to look and see if some hints are available – or leave me a question and I’ll respond to it).

Regarding the exam review sheet, I’ll commit to having the answer key up by Sunday at the latest, but I hope to have it completed sooner (it’s partially done now, at least the first few problems).

Take care,
Mr. Reitz

#16670

hi professor Reitz,
1b i. A student ID at a local university consists of 5 digits plus one letter. How many different IDs are possible? I got 10*10*10*10*10*26= 2,600,000 but you have an extra 10 to equal 26,000,000…. am I doing it wrong?

Edit | Delete #

#16673

kalianne
Participant

Hi professor Reitz
I have a couple of questions about the review sheet. Problem 4A- IV it states “dislikes cats or does not own a dog.” I try to break the problem first. I took the first part about disliking cats which is 36/85 and substituted the word or for addition and then took “does not own a dog” and put 54/85 which gives 90/85. the answer sheet says 72/85. I’m having trouble figuring out why the 72 only comes from the “does not own a dog” column.

Question 9- why is “x” 0.1 and 2 and not just 1 and 2 if it says only two restaurants receive the grade? Also, how do I begin to get P(x)?

#16674

Jonas Reitz
Participant

@America,
For 1b, boy are you right – I have an extra 10 in there! The correct answer is, indeed, 2,600,000. I’ve updated the answer key on the Handouts page.
+1 extra credit!
Mr. Reitz

#16675

Jonas Reitz
Participant

@Valerie, I want to make sure I understand your question about #9 — did you mean to put a decimal in there, “0.1”? Or was it supposed to be a comma, “0, 1 and 2”? Let me know — my response will be different depending on which you meant.
Thanks,
Mr. Reitz

#16676

Jonas Reitz
Participant

@Valerie, Regarding Problem 4A-iv, this problem involves the word “OR”, so the Addition Rule applies. Take a look at the rule, and see if it makes more sense after. If you find that confusing, think of it this way: we want to count everybody who either dislikes cats or who does not own a dog, but we don’t want to count anyone twice…

#16677

kalianne
Participant

For problem #9 I meant 0,1, 2. Sorry about the decimal point.

#16679

Jonas Reitz
Participant

@Valerie – gotcha. In that case, we have to think about what x means: x is the number (out of 2) of restaurants selected that received an “A” grade. Suppose we randomly choose two restaurants — it’s possible that both receive an A grade (x=2), it’s possible that only one of them receives an “A” grade (x=1), and of course it’s possible that neither one receives an “A” grade (x=0) — this is where the 0 comes from. Let me know if this still doesn’t make sense.

#16680

kalianne
Participant

It does make sense, thank you, but how do you start to figure out the frequency?

#16686

Jonas Reitz
Participant

Valerie, I would suggest getting started by making a tree diagram for the problem. This is similar to the example we did at the end of class last Thursday – take a look at your notes if you have them, and try to model what you see. If you’re still stuck let me know.
Regards,
Mr. Reitz

#16832

Anil
Member

Hi!..Good Morning Professor,

here is a pdf of the work for webwork #9….some of the problems still have errors from part A for #6, and #7 through #9

and with part A for #10.

#16833

Anil
Member

i used the conversion for “X” from the “Z” of the ‘area/percent’ for # 7 to 10 though the web work will not accept it.

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