A lock has a code of 4 numbers between 1 and 20. If no numbers in the code are allowed to repeat, how many different codes could be made?

At the olympic games, many events have several rounds of competition. one of these events is the men's 100-meter backstroke. the upper dot plot shows the times (in seconds) of the top 8 finishers in the final round of the 2012 olympics. the lower dot plot shows the times of the same 8 swimmers, but in the semifinal round. which pieces of information can be gathered from these dot plots? (remember that lower swim times are faster.) choose all answers that apply: a: the swimmers had faster times on average in the final round. b: the times in the final round vary noticeably more than the times in the semifinal round. c: none of the above.

Draw a tape diagram to represent each situation. for some of the situations, you need to decide what to represent with a variable andre bakes 9 pans of brownies. he donates 7 pans to the school bake sale and keeps the rest to divide equally among his class of 30 students

You are at a restaurant and owe $56.20 for your meal. you want to leave an 18% tip. approximately how much is your tip?