Abean plant grows at a constant rate for a month. after 10 days, the plant is 25 centimeters tall. after 20 days, the plant is 45 centimeters tall. which equation models the height of the plant, y, after x days?
a. y – 10 = (x – 25)
b. y – 25 = (x – 10)
c. y + 25 = 2(x + 10)
d. y – 25 = 2(x – 10)

There are two major tests of readiness for college: the act and the sat. act scores are reported on a scale from 1 to 36. the distribution of act scores in recent years has been roughly normal with mean µ = 20.9 and standard deviation s = 4.8. sat scores are reported on a scale from 400 to 1600. sat scores have been roughly normal with mean µ = 1026 and standard deviation s = 209. reports on a student's act or sat usually give the percentile as well as the actual score. the percentile is just the cumulative proportion stated as a percent: the percent of all scores that were lower than this one. tanya scores 1260 on the sat. what is her percentile (± 1)?