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It is the same as to subtract from the total area under this curve
part of the area under this curve between the marks z= -1.55 and z= 2.55.
Use function normalcdf of your regular calculator
the area of the interest = 1 - normalcdf(-1.55, 2.55, 0,1) = 1 - 0.934 = 0.066 (rounded). ANSWER
normalcfd stands for normal cumulative distribution function.
z1 z2 mean SD <<<---=== formatting pattern
Its format is normalcdf(-1.55, 2.55, 0, 1).
Solved.