# Global array
declare -a sub_data

# A function to increment counter from startCount to endCount
# and save the number in sub_data array
function run_sub()
{
    subshellIndex=$1
    startCount=$2
    endCount=$3
    while [ 1 ]
    do
        startCount=$((startCount + 1))
        sub_data[$1]=$startCount
        if [ $startCount -ge $endCount ]; then
            echo "Coming out $1"
            break
        fi
        sleep 1
    done
}

function _avg_data()
{
    while true
    do
        local totalValue=0
        for indexValue in "${sub_data[@]}"
        do
            totalValue=$((totalValue + indexValue))
        done
        echo $totalValue
        sleep 4
    done
}

(run_sub "1" "0" "50")&
pid1=$!
(run_sub "2" "100" "150")&
pid2=$!

(_avg_data $sub_data)&
pid3=$!