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(4 points) Determine whether the following are valid probability distributions or not. Enter VALID if it is valid or INVALID if it is not a valid probability distribution. (a) I 5 6 Pr(z) 0.20.6 0.10.1 VALID or INVALID? (b) I 2 5 6 9 Pr(z) 0.4 0.2 0.20.6 VALID or INVALID? (0) I 2 5 6 9 Pr(z) 0.3 0.1 0.20.5 VALID or INVALID? Note: You can eam