i need a script to check if a value is between 2.5 and 4 and to send mail to xyz@gmail if value is greater than 4 send mail to zyx@gmail

i need a shell script to check if a value is between 2.5 and 4 and to send mail to xyz@gmail if value is greater than 4 send mail to zyx@gmail.

i did tried the following but getting error.

test_chk: line 5: [: 1.5: integer expression expected

if [ "$val" -ge 2.5 -a "$val" -le 4 ]; then

if ((1.5<=$val && $val<=3))

then

echo " $val" is abnormal| mailx -s " test " xyz@gmal fi

tried... key1="12.3" result="12.2"

if (( $result <= $key1 )) then # some code here fi