MATH MAT133 6-3 Homework Help Assignment Solutions

MATH MAT133 6-3 Homework Help Assignment Solutions. Homework Problem 3 Let's look at this textbook problem: 7.21 Joan’s finishing time for the Bolder Boulder 10K race was 1.75 standard deviations faster than the women’s average for her age group. There were 405 women who ran in her age group. Assuming a normal distribution, how many women ran faster than Joan? We need to figure out what percent (technically, proportion) of women had a shorter run time. Then we multiply that by 405 to figure out the number of women that were faster. If Joan ran 1.75 standard deviations faster than the other women in her age group then she was 1.75 standard deviations below the average time. The proportion of women who ran faster than Joan is the area under the standard normal curve to the left of 1.75 or P(Z −1.75). We can do this two ways. For this problem, it might be easier to look at the table in appendix c. You see, this table tells you the area to the left of a zscore. To find the area beneath the normal curve to the left of -1.75, look for -1.7 in the row and 0.05 in the column. Check it out: This means that only 4.01% of the women had a faster time. How do we find 4.01% of 405 women? We multiply 405 by 0.0401: .0401•405=16.2405≈16, so only 16 women ran faster than Joan. Here is a video you can watch for Problem 3: Homework Problem 4 Students who score in the top 7 percent are recognized publicly for their achievement by the Department of the Treasury. Assuming a normal distribution, how many standard deviations above the mean does a student have to score to be publicly recognized? Normal Distribution: Top 7% is the same as the bottom 93% Using Excel you would use =NORM.S.INV(p) where p is the area to the left of the z-score.