Average Value

  • #1
How do you find the average value in an experiment when all it consist of is weighing a beaker and adding 10 mL of water three times to it?
 

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  • #2
Math Is Hard
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I am not clear on the procedure. Before each weighing, do you start with an empty beaker and then add 10 mL of water to it? Or do you add more water to the water from the previous weighing each time?
 
  • #3
Math Is Hard said:
I am not clear on the procedure. Before each weighing, do you start with an empty beaker and then add 10 mL of water to it? Or do you add more water to the water from the previous weighing each time?

Before the weighing we do weigh the beaker empty. Adding the 10mL comes afterwards but it happens three times, so it would be 10mL then 20mL then 30mL.
 
  • #4
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That is a very odd exercise. At first I thought it was to demonstrate the margin of human error that you might encounter when weighing the same amount of a substance during consecutive trials, but I am not sure what this is trying to teach.
If you only want an average of the water weights I assume it is
(total weight - beaker weight) for each of the three weighings, summed up and divided by total number of weighings (3), but I better back off here because there might be someone who is more familiar with this exercise.
Did the teacher give any hints about what this would demonstrate?
 
  • #5
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You've got weights for three different 10ml additions do you not? How well can you measure 10 ml?
 
  • #6
Math Is Hard said:
That is a very odd exercise. At first I thought it was to demonstrate the margin of human error that you might encounter when weighing the same amount of a substance during consecutive trials, but I am not sure what this is trying to teach.
If you only want an average of the water weights I assume it is
(total weight - beaker weight) for each of the three weighings, summed up and divided by total number of weighings (3), but I better back off here because there might be someone who is more familiar with this exercise.
Did the teacher give any hints about what this would demonstrate?

Well I figured the average value would be the weight of the beaker empty. Since that is the original state it is in. I don't think that I have to consentrate on the 10mL part and I probably shouldn't have mentioned it. I know this is vague but if the average value isn't given then where else could it come from except for any original state.
 
  • #7
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President Mercury said:
Well I figured the average value would be the weight of the beaker empty. Since that is the original state it is in. I don't think that I have to consentrate on the 10mL part and I probably shouldn't have mentioned it. I know this is vague but if the average value isn't given then where else could it come from except for any original state.
ok, do you know how to compute an average (a mean?)
 
  • #8
Math Is Hard said:
ok, do you know how to compute an average (a mean?)

Yes but isn't this more then just finding the mean?
 
  • #9
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Typically, when people ask for an average value they intend the mean value. (There are also averages of median and mode which are not applicable here.)
 
  • #10
Actually there is also a part that is called deviations from average which I found. The rest of the results are from weighing an empty beaker then adding 10mL of water three times, then we had to find the density of the water and the average density. After that was the deviations from the average.
 
  • #11
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yes, you can also compute a "standard deviation" from your weighings. Now is this a chemistry class or a statistics class?
 
  • #12
Math Is Hard said:
yes, you can also compute a "standard deviation" from your weighings. Now is this a chemistry class or a statistics class?

Chemistry. And I get exactly what you mean so thanks :biggrin:
 
  • #13
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yeah, I can see what you are saying. If you want to get a really good critique (if you have the time and inclination), you could post each question in the assignment, exactly as worded, followed by your answers and explanations of how you came to the conclusions. Then the experts here could go through them one by one.
Chem teachers are quirky. I had one that I bailed on after two classes, and then another who was fantastic and made everything crystal clear.
 
  • #14
I probably should have bailed on this guy. He doesn't even know the english language that well -_-
 

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