Answer
Your friend is correct (it's annoying when that happens!). $69.23%$ of the male students have cell phones, and $64.58%$ of female students do.
Work Step by Step
Let $m =$ total # of male students
$27$ males have cell phones, $12$ do not.
$27 + 12 = m$
$m=39$
$27\div39 = .6923$
$ 0.6923 * 100 = 69.23%$
Let $f = $ total # of female students
$31$ have cell phones, $17$ do not.
$31 + 17 = f$
$48 = f$
$31\div 48 = .6458$
$.6458 * 100 = 64.583%$
Since $64.583\lt 69.23 $, the friend is correct.
