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Let Z be a standard normal random variable and calculate the following probabili

ID: 3219070 • Letter: L

Question

Let Z be a standard normal random variable and calculate the following probabilities, drawing pictures wherever appropriate. (Round your answers to four decimal places.) (a) P(0 lessthanorequalto Z lessthanorequalto 2.23) (b) P(0 lessthanorequalto Z lessthanorequalto 2) (c) P(-2.30 lessthanorequalto Z lessthanorequalto 0) (d) P(-2.30 lessthanorequalto Z lessthanorequalto 2.30) (e) P(Z lessthanorequalto 1.07) (f)P(-1.95 lessthanorequalto Z) (g) P(- 1.30 lessthanorequalto Z lessthanorequalto 2.00) (h) P(1.07 lessthanorequalto Z lessthanorequalto 2.50) (i) P(1.30 lessthanorequalto Z) (j) P(|Z| lessthanorequalto 2.50) You may need to use the appropriate table in the Appendix of Tables to answer this question.

Explanation / Answer

a) P(0 < Z < 2.23) = P(Z < 2.23) - P(Z < 0)

                             = 0.9871 - 0.5

                             = 0.4871

b) P(0 < Z < 2) = P(Z < 2) - P(Z < 0)

                        = 0.9772 - 0.5

                        = 0.4772

c) P(-2.3 < Z < 0) = P(Z < 0) - P(Z < -2.3)

                            = 0.5 - 0.0107

                            = 0.4893

d)P(-2.3 < Z < 2.3) = P(Z < 2.3) - P(Z < -2.3)

                               = 0.9893 - 0.0107

                               = 0.9786

e) P(Z < 1.07) = 0.8577

f) P(Z > -1.95) = 1 - P(Z < -1.95)

                       = 1 - 0.0256

                       = 0.9744

g) P(-1.3 < Z < 2) = P(Z < 2) - P(Z < -1.3)

                            = 0.9772 - 0.0968

                            = 0.8804

h) P(1.07 < Z < 2.5) = P(Z < 2.5) - P(Z < 1.07)

                              = 0.9938 - 0.8577

                                = 0.1361

i) P(Z > 1.3) = 1 - P(Z < 1.3)

                    = 1 - 0.9032

                    = 0.0968

j) P(|Z| < 2.5) = P(-2.5 < Z < 2.5)

                      = P(Z < 2.5) - P(Z < -2.5)

                      = 0.9938 - 0.0062

                      = 0.9876