Question 1081808
mean 800 sd 120
the middle 95% is from z.025 to z.975 which is +/- 1.96
z=(x-mean)/sd
1.96=(x-800)/120
235.2=x-800
x=1035.2 at top end and 664.8 at bottom end
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84th percentile from table is z=+0.95
0.95=(x-mean)/120
114=x-800
914= the critical value
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Half sd above the mean has a score of 860; 900 is 14 points shy of qualifying.
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9 is mostly correct, except 0.3% is double what it should be.  The result is 0.0013 or .13%
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10 is the same at the opposite end, the per cent more than+3 sd, which is not the same as the per cent more than +/- 3 sd.
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11 is correct.
12. We can say that 99.87% work out for no more than 135 minutes.