A cylindrical riser of $6\text{ cm}$ diameter and $6 \text{ cm}$ height has to be designed for a sand casting mould for producing a steel rectangular plate casting of $7 \text{ cm} \times 10 \text{ cm} \times 2 \text{ cm}$ dimensions having the total solidification time of $1.36$ minute. The total solidification time (in minute) of the riser is _______