1. A student reported the mass of 10 glass beads as 2.507 +- 0.015g. What should

Question

1. A student reported the mass of 10 glass beads as 2.507 +- 0.015g. What should the student report as the mass of one bead? Explain your answer

2. A student reported the density of 10 glass beads as 2.05 +- .034 g mL^-1. What should the student report as the density of one glass bead? explain your answer.

3. A student measured the mass of the same ten beads five times instead of using five sets of 10 randomly selected glass beads. Would you expect that the confidence interval for the mean of mass measurement to be zero?

4. A student noticed tat the average diameter of the glass beads used for the mass measuremnets was significanlty smaller than those used for the volume measurements. How would experimental determination of the density of glass be affected? Is this a systematic or random error?

5. Which of the following terms has the greater effect on random error, p(d): the precision of the mass measurements, indicated by [p(m)^/mean mass]^2 ; or the precision of the volume measurements, indicated by [p(v)/ volume mean]^2 ? How might you revise the experimental procedure to reduce this effect?

Explanation / Answer

The first thing we need to divide the weight of the 10 beads by 10

2.507 / 10 = 0.2507 grams

Now we must analyze the confidence interval, we need to know how much error it represents.

0.015 / 2.507 = 0.00598 or 0.598%

So we must report a confidence interval that represents the same porcentage for 1 bead so:

0.00598 * 2.507 = 0.0015 grams

The student must report:

0.2507 +/- 0.0015 grams

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