The penguin exhibit at a zoo has a raised circular island that is surrounded by water. the diameter of the island is  20 meters. one penguin swims half way around the island before hopping out. how far did the penguin swim?

Asurvey of 45 teens found that they spent an average of 25.6 hours per week in front of a screen (television, computer, tablet, phone, based on the survey’s sample mean, which value could be the population mean? 2.3 hours 27.4 hours 75.3 hours 41.5 hours

The two square pyramids are similar. find the total volume of both pyramids if the ratio of their surface areas is 9/16

Donald has x twenty-dollar bills and 11 ten-dollar bill. how much money does donald have? write your answer as an expression.