判断当前循环到的这条试题的答对次数

Question

Array ( 
 [14] => Array ( [ok] => 1 [err] => 1 ) 
 [15] => Array ( [ok] => 1 [err] => 0 ) 
)

我想判断当前循环到的这条试题的错误率，ok是答对的，err是答错的

Answer 1

错误率值 ？
err / (err + ok) ？

Answer 2

$err = 0
$ok  = 0

foreach ($arr as $k => $v) {
    $ok  += $v[ok];
    $err += $v[ree];
}

echo $err / ($err + $ok);