A plant grows 1.8 centimeters a month. There are 12 months in a year. How many centimeters will the plant grow in one year? Miss Riley believes that it will be 21.6 cm. Is she correct?

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6