A national polling organization wants to be 95% confident that its estimate of the percent of registered voters who say they plan to vote for a particular candidate will be within three percentage...

A    national    polling    organization    wants    to    be    95%    confident    that    its    estimate    of    the    percent    of
registered    voters    who    say    they    plan    to    vote    for    a    particular    candidate    will    be    within    three
percentage    points    (.03)    of    the    true    proportion    that    plan    to    vote    for    her.
a) How    large    a    sample    do    they    need    if    the    number    of    registered    voters    who    plan    to    vote    for    her
is in    fact    around    50%?
b) How    large    a    sample    will    they    require    for    a    margin    of    error    of    just    one    percentage    point
(.01)?