Answer
The temperature in the lake on June 9 (day 160) at a depth of 10 m is approximately 11°C and on June 29 (day 180) at a depth of 5 m is about 19.5°C.
Work Step by Step
Point (160,10), corresponding to day 160 and a depth of 10 m, lies between 8°C and 12°C. Since the point appears to be located about 3/4 the distance from the 8°C to the 12°C isothermal, we estimate the temperature at that point to be about 11°C. Point (180,5) lies between the 16°C and 20°C, very close to the 20°C level curve, so we estimate the temperature there to be about 19.5°C.
