A certain spring has a spring constant k1 = 720 N/m as the spring is stretched from x = 0 to x1 = 39 cm. The spring constant then changes to k2 = 210 N/m as the spring is stretched to x2 = 67 cm. From x2 = 67 cm to x3 = 91 cm the spring force is constant at F3 = 115 N.

The temperature at a point (x, y) is t(x, y), measured in degrees celsius. a bug crawls so that its position after t seconds is given by x = 6 + t , y = 8 + 1 3 t, where x and y are measured in centimeters. the temperature function satisfies tx(3, 9) = 5 and ty(3, 9) = 4. how fast is the temperature rising on the bug's path after 3 seconds? (round your answer to two decimal places.)