Finding Average and Total Score in Exam with Static Array

<?php

// Nilai besar-kecil
echo "<br><br>";
$arr = array();
$arr2 = array();
$arr[0] = 93;
$arr[1] = 100;
$arr[2] = 57;
$arr[3] = 54;
$arr[4] = 94;
$arr[5] = 79;
$arr[6] = 92;
$arr[7] = 99;

$arr2[0] = "wayan";
$arr2[1] = "putu";
$arr2[2] = "gede";
$arr2[3] = "made";
$arr2[4] = "kadek";
$arr2[5] = "komang";
$arr2[6] = "nyoman";
$arr2[7] = "ketut";

$temp=0;
$temp1=100;

for ($i=0; $i <8 ; $i++) {
    ($temp<$arr[$i])?($temp = $arr[$i] AND $tempName = $arr2[$i]):'';
    ($arr[$i]<$temp1)?($temp1 = $arr[$i] AND $tempName1 = $arr2[$i]):'';
}

echo "<br>";
echo "Terbesar : <br><b style='text-transform: capitalize;'>$tempName</b> :  $temp<br><br>Terkecil : <br><b style='text-transform: capitalize;'>$tempName1</b> :  $temp1";

// Nilai rata-rata
echo "<br><br>";
echo "Nilai Rata-Rata<br>";

$arr3 = array();
$arr4 = array();
$arr3[0] = 80;
$arr3[1] = 87;
$arr3[2] = 94;

$arr4[0] = 61;
$arr4[1] = 57;
$arr4[2] = 66;

for ($i=0; $i<3 ; $i++) {
    $avg = ($arr[$i]+$arr3[$i]+$arr4[$i])/3;
    echo "<b style='text-transform: capitalize;'>$arr2[$i]</b> : ".floatval(number_format($avg,2))."<br>";
}

// Nilai akhir
echo "<br><br>";
echo "Nilai Akhir<br>";

for ($i=0; $i<3 ; $i++) {
    $avg = ($arr[$i]+$arr3[$i]+$arr4[$i])/3;
    ($avg>90)?$grade = "A":($avg>70)?$grade = "B":$grade = "C";
    echo "<b style='text-transform: capitalize;'>$arr2[$i]</b> : $grade<br>";
}