For a certain examination, a score of 58 was 2 standard deviation below the mean, and a score of 98 was 3 standard deviation above the mean. What was the mean score for the examination?
74
*I don’t know why standard deviation is such a problem for me
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Standard Deviation
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scoobydooby
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98=M+3SD..............1
58=M-2SD...............2
subtracting 2 from 1 we get 40=5SD=> SD=8
replacing in either 1 or 2 we get M=74
58=M-2SD...............2
subtracting 2 from 1 we get 40=5SD=> SD=8
replacing in either 1 or 2 we get M=74
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ssmiles08
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you know another helpful way is just draw out a small diagram:
58 (2)---(1)---(0)----(1)----(2)----(3) 98
total distance is 5 std. deviations
so its 98 - 58 = 40
40/5 = 8.
each st. dev is 8 units apart. We also know (0) is the mean. so 58 + 16 = 74
58 (2)---(1)---(0)----(1)----(2)----(3) 98
total distance is 5 std. deviations
so its 98 - 58 = 40
40/5 = 8.
each st. dev is 8 units apart. We also know (0) is the mean. so 58 + 16 = 74
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gauravkhare
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you know another helpful way is just draw out a small diagram:
58 (2)---(1)---(0)----(1)----(2)----(3) 98
total distance is 5 std. deviations
so its 98 - 58 = 40
40/5 = 8.
each st. dev is 8 units apart. We also know (0) is the mean. so 58 + 16 = 74
GOOD ONE!!!!
58 (2)---(1)---(0)----(1)----(2)----(3) 98
total distance is 5 std. deviations
so its 98 - 58 = 40
40/5 = 8.
each st. dev is 8 units apart. We also know (0) is the mean. so 58 + 16 = 74
GOOD ONE!!!!
gaurav
