Study the probability table in the image . Which two sums have the least probability

Acity plans to build a new rectangular-shaped park. the perimeter of the park will be 940 meters. the width of the park will be 300 meters. what will be the length, in meters, of the new park?

The size of a certain cell is 2.5*10^-9m. another cell is 1.5*10^3 times larger. how large is the larger cell in scientific notation?

The tile along the edge of a triangular community pool needs to be replaced? ?