A double$-$pipe parallel$-$flow heat exchanger is used to heat water $(C_p=4180\frac{J}{k}gK$ from $25C$ to $60C$ at a rate of $0\mathrm{.}2k\frac{g}{s}.$ The heating is accomplished by geothermal water $(c_p=4310\frac{J}{k}gK)$ available at $136C$ at a mass flow rate of $0\mathrm{.}3k\frac{g}{s}.$ The inner tube is thin$-$wailed and has a diameter of $0\mathrm{.}8$ cm $.$ If the overall heat transfer coefficient of the heat exchanger is $550\frac{W}{m^2}.K,$ determine the length of the tube required to achieve the desired heating. $($Round the answer to a single decimal place.$)$

The length of the lube required to achieve the desired heating is $-$ m