So they get $2 on day 0, $2 on day 2, $3 on day 4, $5 on day 5, $2 on day 6, $1 on day 7, $2 on day 8, $4 on day 10, $1 on day 11, $2 on day 12 and $1 on day 15.
$2 appears 5 times
$1 appears 3 times
$4 appears once and $5 appears once
The median would be ($2*5 + $1*3 + $4 + $5)/(5+3+1+1) = $22/10 = $2.2
The range of the allowances is highest - lowest = $5-$1 = $4
Edit: It might also have a range of $5 and a median of $1.37 because the lowest it goes to is $0 on some days though. Try both.