To find the mean of a group of data, you add up all of the numbers and divide the total by the amount of numbers there are. In this case, you have 15,11,10,11,14,10,15,10,and 12.
Well, to get the surface area, you do length x width x height. <span>Multiply the side length of the base by the slant height and divide by two. Then, multiply by 4. This will give you the lateral </span>surface area<span> of the </span>pyramid<span>.</span>