Please help me with this one show me how u get it and the answer please I really I need help please

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

Need 50 will mark brainliest answer. find the lengths of all the sides and the measures of the angles.

The figures below are made out of circles, semicircles, quarter circles, and a square. find the area and the perimeter of each figure and give your answers as a completely simplified exact value in terms of π (no approximations).