New Problems Proposed

Last year I changed Unit 2 but did not write replacements for problems 2-4 and 2-5.  Here are two PROPOSED problems. They are not assigned this year but I post them here for the record and discussion.

SP2-4

Make a table showing the probabilities that the sum of the roll of 3 dice are  3, 4, 5, 6, 7, ...18. You have already done 11 in the activity guide. Explain your method of calculation. Hint: You can use a symmetry argument to shorten the calculations. The probability for getting 3 is the same as for 18, the probability of getting 4 is the same as for 17, etc. 

SP2-5

Instead of measuring the background level in one run of 80 1-minute intervals you do 2 experiments, measuring 30 1-minute intervals and then 50 1-minute intervals. The results are as follows:

  30 intervals: average = 11.8 counts/minute, SD = 4.2  counts/minute

  50 intervals: average = 12.2 counts/minute, SD = 3.8 counts/minute

Use the formulas for the average and Standard Deviations to determine what the average and SDs would have been if you had done this experiment as a single experiment of 80 1-minute intervals.