Me 15p for an answer and brainliest mme the true it is 20p

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

72 the length of a side of a triangle is 36. a line parallel to that side divides the triangle into two parts of equal area. find the length of the segment determined by the points of intersection between the line and the other two sides of the triangle.

Mrs. blake's bill at a restaurant is $42.75. she wants to leave the waiter an 18% tip. how much will she pay in all, including the tip?