oil is leaking out of a tank. the depth of oil in the tank for 60 seconds is shown below. use the graph to work out the rate of decrease of depth, in cm/s, at 10 seconds. you must show your working.

Which graph represents 2x-5y< 15

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

The head librarian at the library of congress has asked her assistant for an interval estimate of the mean number of books checked out each day. the assistant provides the following interval estimate: from 740 to 920 books per day. what is an efficient, unbiased point estimate of the number of books checked out each day at the library of congress?