Find The Following, Please Help Me !! ( Geometry)

You are remodeling your kitchen. you’ve contacted two tiling companies who gladly told you how long it took their workers to tile of a similar size jim completed half the floor in 8 hours. pete completed half of the other floor in 7 hours. if pete can lay 20 more tiles per hour than jim, at what rate can jim lay tiles

The standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?

What is the product? a-3/15a × 5/a-3