Final answer:
The student's question covers mathematical concepts such as simplifying fractions, calculating z-scores, understanding standard deviations, and determining sample sizes in statistics.
Step-by-step explanation:
The question appears to be asking for help with several mathematics problems involving simplification of fractions, calculation of z-scores, and understanding standard deviations in statistics. One of the problems presented is correctly simplifying the fraction 12/15, which simplifies to the fraction 4/5. Another part deals with z-scores and standard deviation, specifically the calculation involving x = 17 which is two standard deviations to the right of the mean, implying a z-score of 2 since one standard deviation is given as 6 (μ + 2σ = x).
Sample size calculation appears as well using a formula that factors in the standard deviation, margin of error, and z-score for a desired confidence level, leading to n = 217. The instruction is to always round up the sample size to ensure its adequacy.