What is the length of EF in the right triangle below 18 12

Which of the following is the result of expanding

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

At noon a tank contained 10cm water. after several hours it contained 7cm of water. what is the percent decrease of water in the tank?