Question

At 9:00 a.m. Monday morning, Thomas fills a beaker with water and places it in the corner of the classroom. At 1:00 p.m. on Tuesday, Thomas examines the beaker and notices that the water level is 42 milliliters. At 11:00 a.m. on Wednesday, the water level has dropped to 31 milliliters. If the evaporation of the water follows a linear function, at what time will the beaker be empty?

Answer 1

Let y = level and x = time.

Call 1:00 pm Tuesday time 0.
At time 0, the water level is 42 mm.
This gives you one ordered pair, (0, 42).

11:00 am on Wednesday is 22 hours after time 0.
At time 22 hours, the level is 31 mm.
This gives you a second ordered pair, (22, 31).

Use the 2 ordered pairs to find the equation of a line.
After you have the equation of the line, find at what time, x, the level, y, is zero.
Then add that number of hours to 1:00 pm Tuesday to find the time and day when the beaker will be empty.

Answer 2

Thank you!

Answer 3

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