GEOMETRY HELP PLEASE

What is the exact area of a circle with a diameter of 50 centimeters? a.87.9 square centimeters b.379.9 square centimeters c.1962.5 square centimeters d.4923.5 square centimeters

Which linear equations have an infinite number of solutions? check all that apply.  (x  –  3/7)  =  2/7(3/2x  –  9/14)8(x  +  2)  =  5x  –  1412.3x  –  18  =  3(–6  +  4.1x)(6x  +  10)  =  7(x  –  2)4.2x  –  3.5  =  2.1 (5x  +  8)

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3. be sure to show that you know the formula and how to plug into it. also, clearly state the margin of error.