Mean mark #2

Chapter 3 - Question 3

Design a program to compute the mean mark from input data giving the number of students in a class followed by a list of their marks.

Solution 1

<?
// * DATA CREATION

// a random number of students
$students = mt_rand(5, 15);

// for each student, generate a random mark
for ($n = 0; $n < $students; $n++)
$marks .= ' ' . mt_rand(0, 10);

// join everything together
// so this is like [total] [mark1] [mark2] ...
$data = $students . $marks;

// * PROCESSING

// first, split everything up
$data = explode(' ', $data);

// the total number of students is the first item of data
// the rest of the array is the marks
// divide the total by the students to get the average
$prc_average = array_sum(array_slice($data, 1, count($data)-1)) / $data[0];

// * OUTPUT

echo 'Data: ' . implode(' ', $data) . '<br/>' .
'Students: ' . $data[0] . '<br/>' .
'Average mark: ' . round($prc_average, 4);
?>

Which produces:

Data: 6 10 8 6 3 6 0
Students: 6
Average mark: 5.5

Solution 2

There's no need for anyone to enter the number of students. That can easily be worked out from the number of marks given. Here's a simpler version that outputs the same thing but uses a lot less code.

<?
// * DATA CREATION

// generate a random mark for a random number of students
for ($n = 0; $n < mt_rand(5, 15); $n++)
$scores[] = mt_rand(0, 10);

// * OUTPUT & PROCESSING

echo 'Data: ' . count($scores) . ' ' . implode(' ', $scores) . '<br/>' .
'Students: ' . count($scores) . '<br/>' .
'Average mark: ' . round(array_sum($scores) / count($scores), 4);
?>

Which produces:

Data: 10 5 10 4 6 7 1 8 3 10 1
Students: 10
Average mark: 5.5

Log

May 2, 2005 - Added solution 1 and 2.