Question 1180794
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Hi
Normal Distribution:  µ = 490 and  σ  = 100 
Using TI or similarly an inexpensive calculator like a Casio fx-115 ES plus
Continuous curve

P(390 > x > 590)= normalcdf(390, 590, 490, 100) = .6827  0r 68% (2 decimal places)
Keisan Online Calculator
   *[illustration 5_22.png].

P(-1.3 > z > 8.99)= normalcdf(-1.3, 8.99, 0, 1) = .90 (2 decimal places)

{{{ME = z*sigma/sqrt(n)}}}
 As n gets larger...ME gets smaller
 As z gets larger(n the same) ...ME gets larger
 = CI	z = value
90%	z =1.645
92%	z = 1.751
95%	z = 1.96
98%	z = 2.326
99%	z = 2.576

Important You feel comfortable using Your calculator.
Wish You the Best in your Studies.

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