Math help needed :)

[lewber]

Is this question written correctly?

 

Thanks all! You confirmed my thoughts. Wanted to make sure I wasn't missing anything. 

Edited December 1, 2017 by lewber

[regentrude]

The first question should be worded more precisely and state that h is the height *above the ground* in meters. Then you solve by setting h=0 and solving for t.

Edited December 1, 2017 by regentrude

[kiana]

Are you supposed to do the second one on a graphing calculator? 

[Arcadia]

For the correlation coefficient of the regression question, write out a table for the four sets of values. Then solve similar to page 7 & 8 of link http://www.cimt.org.uk/projects/mepres/alevel/stats_ch12.pdf

 

It would be tedious by hand and much easier with a scientific calculator or any calculator with a statistics function. You won’t need a graphing calculator for that question.

[kiana]

The answer for the correlation coefficient (just calculated it by hand) is sqrt(14/15). I googled the problem -- there are several different packets out there including this question, but every one of them is primarily about linear functions with a few questions about stats and a few more advanced questions. There is absolutely no way that this is supposed to be a calculator-free question. OP, I think if you were given this and told it was calculator-free, it was because the teacher didn't check it carefully first and realize that there were a few stats questions that were supposed to be done with a calculator. Edit: Or possibly verbally instructed the students to skip those questions and the student didn't hear. 

 

Edit again: Writing sqrt (14/15) as sqrt(210)/15, and using that 14 < sqrt 210 < 15 and that 14/15 = 0.933... , I can guess (without extracting square roots by hand because I'm not that masochistic) that 0.933... < r < 1, and that will let me choose the correct multiple-choice answer. But I don't think this is a reasonable level of calculation/reasoning to expect from students who (looking at the rest of the questions) are probably average 9th graders. 

Edited December 1, 2017 by kiana

[Tanaqui]

Wait. Isn't acceleration due to gravity on earth 9.4 meters per second squared? You've transposed those digits!

 

Edit: Just did a google check. It is, in fact, 9.8. Where'd 4.9 come from?

 

Edit again: Nevermind. I know math, but evidently my physics is a bit rusty. Thank goodness for google.

 

Edited December 1, 2017 by Tanaqui

[lewber]

The answer for the correlation coefficient (just calculated it by hand) is sqrt(14/15). I googled the problem -- there are several different packets out there including this question, but every one of them is primarily about linear functions with a few questions about stats and a few more advanced questions. There is absolutely no way that this is supposed to be a calculator-free question. OP, I think if you were given this and told it was calculator-free, it was because the teacher didn't check it carefully first and realize that there were a few stats questions that were supposed to be done with a calculator. Edit: Or possibly verbally instructed the students to skip those questions and the student didn't hear. 

 

Edit again: Writing sqrt (14/15) as sqrt(210)/15, and using that 14 < sqrt 210 < 15 and that 14/15 = 0.933... , I can guess (without extracting square roots by hand because I'm not that masochistic) that 0.933... < r < 1, and that will let me choose the correct multiple-choice answer. But I don't think this is a reasonable level of calculation/reasoning to expect from students who (looking at the rest of the questions) are probably average 9th graders. 

 

 

It was on a previous year's 9th grade math competition test we were using to prepare for this year's competition. No calculators are allowed and he has never covered that subject in class. So, I was wondering what I was missing. Thanks for the help!