In: Math
1.
Let X be the random variable and be mean and be the std. deviation.
X ~ N(, 2)
Std. normal variable, Z = (X-)/.......1
P(-2* < X < +2*) = P(-2<Z<2) [by converting X into Z using the above formula in 1]
= 0.9545
2.
x = +3*
P(X<+3*) = P(Z<3) [by converting X into Z using the above formula in 1]
= 0.9987
3.
Combinations = 9!
= 362880
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