bio 205l analysis 1

# bio 205l analysis 1 - 1 a Our data shows the 125-mL...

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of Mean (0.45%), meaning that this should be the most accurate measuring device. This is false in most cases, though, because the 100-mL graduated cylinder should be the most accurate device because it is more calibrated, in other words, it has more measuring ticks. b. From the data collected in Section 1.3, one cannot easily determine the precision because measurements were only taken three times, and precision is the consistency a number is reproduced. We would need to do more trials and calculate the standard deviation of the mean to determine the precision. The smallest number calculated from the standard deviation would be the most precise. 2. a. · The class data has a mean closer to the target value of 9-mL. Our group mean was 8.48-mL and the class data was 8.68-mL. · The percent error of the mean indicates accuracy. · The class data is more accurate because its percent of the mean is 0.04% and our group was 0.06%. The smaller percentage indicates that it deviates less from the target value. · The statistic indicating precision is standard deviation. · Our group data is more precise because we have a smaller standard deviation. We used the same balance for all measurements, which could indicate why all of them were similar, even though with larger sample sizes, there are more chances the samples have to be the average value. b. · The percent error is less for the 10-mL glass Blow-out pipet, so this device is more accurate. The pipet is skinnier and the calibrations are further apart so it is easier to see that the bottom of the meniscus is touching the correct measurement line. Also, the amount of water being taken into the pipet can be controlled, rather than poured in. · The cylinder has a lower standard deviation, meaning that it is more precise. The reason for this could be because the blow out pipet is a relatively new device for many students, so some may have bubbles form in their pipet, whereas the graduated cylinder is easy to obtain the same measurement because its an easier process; water is poured inside. 3. 4. a. The assumed null hypothesis is that these two sets of data are the same for both the cylinder and the pipet because it’s the same 9-mL measurement. b. The group data mean was 8.48 +/- 0.08-mL for the 10-mL graduated cylinder. The group data mean was 9.38 +/- 0.66-mL for the 10-mL glass Blow-out pipet. P-value was 0.1388 The class data mean was 8.62 +/- 0.12-mL for the 10-mL graduated cylinder. The class data mean was 8.95 +/- 0.33-mL for the glass Blow-out pipet. P-value was .00081314 c. Group data: No, meaning the null hypothesis is not rejected and the two sets of data are not statistically different. They could be similar by chance because the sample size is so small, so there were less chances for differing measurements. Also, the same balance was used, whereas, in a larger sample size with different balances, as in the

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bio 205l analysis 1 - 1 a Our data shows the 125-mL...

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