Find the following probabilities for a standard normal random variable z :
P(-1 <= z<= 1)
P(-1 <= z<= 1)
1 Answers
Best Answer
Definitions
Complement rule:
P(A^(C))=P(not A)=1-P(A)
Addition rule for disjoint or mutually exclusive events:
P(A ∪ B)=P(A or B)=P(A)+P(B)
Solution
The probability P(0<= z<= 1) is given in the row with z=1.0 and in the column with .00 of the normal probability table in the appendix:
P(0<= z<= 1)=0.3413
The standard normal distribution is symmetric about 0:
P(-1<= z<= 1)=2P(0<= z<= 1)=2(0.3413)=0.6826