Question

The temperature of water in a certain lake on a day in October can be determined by using the model y=15.2-0.537x where x is the number of feet down from the surface of the lake and y is the Celsius temperature of the water at that depth. Based on this model, how deep in the lake is the water 9 degrees? (Round to the nearest foot.) a. 12 c. 67 b. 45 d. 30

Answer 1

y=15.2-0.537x    substitute 9 for y

9=15.2-0.537x    add .537x to both sides and subtract 9 from both sides
.537x =6.2          divide both side by .537
x= 11.545            round it to 12

Answer 2

The water is 9 degrees at a depth of 12 feet