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Question 22, 55.33.3030\newlinePoints\newlinexx Points: 00 of 11\newlineFind the \newlinezz-scores for which \newline15%15\% of the distribution's area lies between \newlinez-z and \newlinezz.\newlineClick to view pace lof the table Click to view page 22 of the table.\newlineThe \newlinezz-scores are \newline\square.\newline(Use a comma to separate answers as needed. Round to two decimal places as needed.)

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Q. Question 22, 55.33.3030\newlinePoints\newlinexx Points: 00 of 11\newlineFind the \newlinezz-scores for which \newline15%15\% of the distribution's area lies between \newlinez-z and \newlinezz.\newlineClick to view pace lof the table Click to view page 22 of the table.\newlineThe \newlinezz-scores are \newline\square.\newline(Use a comma to separate answers as needed. Round to two decimal places as needed.)
  1. Understand total distribution area: To find the z-scores for which 15%15\% of the distribution's area lies between z-z and zz, we need to understand that the total area under the standard normal distribution curve is 11 (or 100%100\%). Since we are looking for the area in the middle of the curve, we need to first determine the area in one tail to exclude.
  2. Calculate excluded tail area: The area we want to exclude from each tail is half of 15%15\%, because we are looking for the area between z-z and zz, which is symmetrical around the mean. So, we calculate 15%/2=7.5%15\% / 2 = 7.5\% for each tail.
  3. Find z-score for 8585% distribution: Now we need to find the z-score that corresponds to the area to the left of z that includes the middle 85%85\% of the distribution (100%15%=85%100\% - 15\% = 85\%). Since the distribution is symmetrical, we want the area to the left of z to be 85%/2=42.5%85\% / 2 = 42.5\% plus the 7.5%7.5\% in the lower tail, which totals 50%50\%.
  4. Lookup z-score for 0.92500.9250 area: Using a standard normal distribution table or a calculator with inverse normal distribution function, we look up the z-score that corresponds to an area of 0.5000+0.4250=0.92500.5000 + 0.4250 = 0.9250 to the left of zz.
  5. Identify positive and negative z-scores: The z-score that corresponds to an area of 0.92500.9250 to the left is approximately 1.441.44. This is the positive z-score. Since the normal distribution is symmetrical, the negative z-score is 1.44-1.44.
  6. Final z-scores for 1515% area: Therefore, the z-scores for which 1515% of the distribution's area lies between z-z and zz are approximately 1.44-1.44 and 1.441.44.

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