Question 1191929: for a normal distribution if the value of mean is 70 and standard deviation is 15.75 find the points
(a) in which it contains 98% area between them
(b) in which it contains 95% area between them
(c) in which it contains 85% area between them
(d) in which 60% area between them
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 98% of the area between want z of 0.01 and 0.99 which is +/-2.326
95% of the area is z +/-1.96
85% of the area is between -0.075 and 0.925 for z of +/-1.44
60% of the area is between 0.2 and 0.8 for z of +/- 0.8416
z=(x-mean)/sd
2.326=(x-70)/15.75
x-70=36.63
x=106.63 and the other value is 33.37. (33.37, 106.63)
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the second one is mean+/-1.96*15.75=30.87 (39.13, 100.87)
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the third one is mean +/-22.68 (47.32, 92.68)
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the fourth one is mean +/-0.8416 =13.26 for (56.74, 83.26)
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