Question 1053419: I have this question from my homework can you please help me understand it and how to solve it? The test scores of 30 students are listed below. Which number could be the 30th percentile?
31 41 45 48 52 55 56 56 63 65
67 67 69 70 70 74 75 78 79 79
80 81 83 85 85 87 90 92 95 99
A) 64
B) 90
C) 56
D) 67
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! When looking for a percentile follow this procedure, we will use 30 percentile from our problem
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1) divide 30 by 100 = 0.30
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2) add 1 to the number of data elements, 30 + 1 = 31
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3) calculate 0.30 * 31 = 9.3
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4) since the result in 3) is not a whole number, we have an integer part(9) and decimal part(.3). We add 1 to the integer part = 9 + 1 10
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5) We then lookup the 9th and 10th lowest scores. They are 63 and 65.
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6) We calculate their difference 65 - 63 = 2. Multiply this difference by the decimal portion in step 3, 2 * 0.3 = 0.6
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7) We add this result to the raw integer portion, the integer portion 9 and the 9th lowest score is 63. We have 63 + 0.6 = 63.6
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The closest value to 63.6 is A)
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