Use the Pythagorean theorem. The equation for this right triangle would be a^2+b^2=c^2. Since you have one leg and the hypotenuse, you can plug these into the equation. It would be 7^2+b^2=12^2. Do the exponents. You will get 49+b^2=144. You need to get b by itself so subtract each side by 49. You get the equation b^2=95. Square root each side to get b=9.746. This rounds to 9.7. So the answer is A. Hope this helps! ;)
if you add all the numbers together, you would get 336. since there are eight numbers in the data set, you should divide it by eight.. with that said, 336/8 is 42
