Evaluate the cumulative distribution function, f, for the given random variable, x, at specified values; also determine the requested probabilities. f left-parenthesis x right-parenthesis equals left-parenthesis 343divided by 57right-parenthesis left-parenthesis 1 divided by 7right-parenthesis superscript x, give exact answers in form of fraction. upper f left-parenthesis 1 right-parenthesis equals upper f left-parenthesis 2 right-parenthesis equals upper f left-parenthesis 3 right-parenthesis equals (a) upper p left-parenthesis upper x less-than-or-equal-to 1.5 right-parenthesis equals (b) upper p left-parenthesis upper x less-than-or-equal-to 3 right-parenthesis equals (c) upper p left-parenthesis upper x greater-than 2 right-parenthesis equals (d) upper p left-parenthesis 1 less-than upper x less-than-or-equal-to 2 right-parenthesis equals