GROWTH DEVELOPMENT CHILD
INDIVIDUAL DIFFERENCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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2%
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14%
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34%
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68%
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97%
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Detailed explanation-1: -Based on the 68-95-99.7 Rule, approximately 68% of the individuals in the population have an IQ between 85 and 115.
Detailed explanation-2: -68% of people have IQs between 85 and 115 (100 +/-15). 95% have IQs between 70 and 130 (100 +/-(2*15). 99.7% have IQs between 55 and 145 (100 +/-(3*15).
Detailed explanation-3: -115 is one standard deviation above the mean, i.e., z = 1.0. So, by the table, 34.13% of the population has an IQ score between 100 and 115. Since 50% is supposed to be above the average of 100 (by symmetry), this means 50-34.13 = 15.87 (%) has an IQ score above 115.
Detailed explanation-4: -Because the curve is symmetric, half (16%) will be in each tail. Thus, the percentage of IQ scores less than 115 is about Page 7 7 68% + 16% = 84%. (5) To determine the percentage of scores above 130, we follow a similar procedure. We know that about 95% of IQ scores are between 70 and 130.
Detailed explanation-5: -We know that 95% of scores fall between 80 and 120 so 5% must fall outside this range. Half of these, 2.5%, will be below 80. Therefore we would expect that 2.5% of people to have IQ scores less than 80.