下面的shell脚本中有什么错误：

#!/bin/bash

total=0

for i in 1 2 3 4
do
    echo -n "Enter Passenger Name: "
    read pname
    
    echo -n "Enter Car Number: "
    read ncar

    echo -n "Enter Amount: "
    read amount

    echo -n "Enter Distance Travelled: "
    read dtravelled

    total=$((total + dtravelled))

    average=$(echo "$total 4" | awk '{print $1/$2}')

    if test $dtravelled -gt 10000 -a $dtravelled -le 7000
    then
        bpassenger=$((business_pass + 1))
    elif test $dtravelled -gt 7000 -a $dtravelled -le 5000
    then
        lpassenger=$((leisure_pass + 1))
    else
        opassenger=$((other_pass + 1))
    fi

    if test $i -eq 1
    then
        lname=$pname
        low=$dtravelled
    fi

    if test $dtravelled -lt $low
    then
        lname=$pname
        low=$dtravelled
    fi
    
    echo
done

echo "Total of distance travelled by the passengers: $total"
echo "Average distance travelled by the passengers: $average"
echo "Number of business passengers: $bpassenger"
echo "Number of leisure passengers: $lpassenger"
echo "Number of other passengers: $opassenger"
echo "lowest distance travelled is $low by $lname."

***未计算下面的块***在此计算中总是得到空输出

if test $dtravelled -gt 10000 -a $dtravelled -le 7000
        then
            bpassenger=$((business_pass + 1))
        elif test $dtravelled -gt 7000 -a $dtravelled -le 5000
        then
            lpassenger=$((leisure_pass + 1))
        else
            opassenger=$((other_pass + 1))
        fi

输出：

bash mySript.sh

Enter Passenger Name: ahmad
Enter Car Number: 9889
Enter Amount: 20
Enter Distance Travelled: 1100

Enter Passenger Name: sara
Enter Car Number: 5214
Enter Amount: 300
Enter Distance Travelled: 1120

Enter Passenger Name: mohammad
Enter Car Number: 9713
Enter Amount: 6
Enter Distance Travelled: 500

Enter Passenger Name: nora
Enter Car Number: 98765
Enter Amount: 41
Enter Distance Travelled: 7500

Total of distance travelled by the passengers: 10220
Average distance travelled by the passengers: 2555
***Number of business passengers:*** 
***Number of leisure passengers:*** 
Number of other passengers: 1
lowest distance travelled is 500 by mohammad.