Pls help I’ll brainlest and add extra points do 1-7

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.

Y=21.95x+10 y=22.45x solve by substitution

At the beginning of a call to the cable company, a message tells customers, "after you finish talking to our customer service representative, you will be asked to take a five-question survey about the level of service you recieved. it would be appreciated if you could stay on the line to answer the survey questions." what type of sampling is the cable company using?