Answers_for_exercises_on_Z_scores

Answers_for_exercises_on_Z_scores - 3. a) 50%, b) 16%, c)...

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Answers for exercises on Z scores 1. a) From normal curve table, top 5% (45% between mean and Z score) begins at 1.64 (or you can use 1.65). Thus, the corresponding raw score is X = (Z) (SD) + M = (1.64) (2.8) + 15.3 = 19.89. b) From normal curve table, bottom 10% (40% between mean and Z score) begins at 1.28. Thus the corresponding raw score is (-1.28) (2.8) + 15.3 = 11.72. 2. a) Z = 740 500 / 100 = 2.4. From the normal curve table, 1% scored higher, b) 99% scored lower. c) Z = 380 500 / 100 = -1.2. From the normal curve table, 88.49% scored higher, and d) 11.51% scored lower.
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Unformatted text preview: 3. a) 50%, b) 16%, c) 98%, d) 84%, e) 50%, f) 84%, g) 2%, h) 16%. 4. a) 340: z = 340-300/20 = 2 b) 310: z = 310-300/20 = 0.5 c) 260: z = 260-300/20 = -2 d) 2.4: x = 2.4(20) + 300 = 348 e) 1.5: x = 1.5(20) +300 = 330 f) 0: x = 0(20) + 300 = 300 g)-4.5: x = -4.5(20) + 300 + 210 5. a) The top 10% means 90% are below. Of this 90%, 50 % are below the mean. Thus, the top 10% is the point where 40% of scores are between it and the mean. Looking this up in the normal curve table, 40.00 (the closest actual value is 39.97) is a Z score of 1.28. b) 2.33...
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