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?

01:00 a.m. Saturday
The time elapsed between 1:00 p.m. on Tuesday when the water level was at 42 milliliters and 11:00 a.m. on Wednesday when the water level was at 31 milliliters is 22 hours. There is an 11-milliliter difference between the two recordings, and 11/22 = 1/2, so every hour, the water level drops 0.5 mL.

If an hour is represented by x, then the linear equation  can represent how much water is left in the beaker in mL after Wednesday's reading at 11:00 a.m. Since we want f(x) = 0, we have to figure out what value of x will cause that by setting up the equation. , when solved for x, will give that value.

First, subtract 31 from both sides, then divide everything by -0.5 to get that . This means that after 62 hours after 11:00 a.m. on Wednesday, the beaker will be empty.

62 hours after 11:00 a.m on Wednesday is 1:00 a.m. on Saturday. 48 hours is 2 full days after Wednesday, or Friday at 11:00 a.m. Adding 12 hours (for a total of 60 hours elapsed) brings you to 11:00 p.m., still on Friday. Finally, the remaining two hours, when elapsed, bring you to the exact moment the water evaporates - 1:00 a.m. Saturday.