What is another word for magnitude?

In a singing competition, there are 150 participants. at the end of each round, 40% of the participants are eliminated. how many participants are left after n rounds?

If it 8 inch candle burns at 7/10 inch per hour and a 6 inch candle burns at 1/5 inch per hour after how many hours would both candles be the same height

Kelli swam upstream for some distance in a hour. she then swam downstream the same river for the same distance in only 6 minutes. if the river flows at 5km/hr, how fast can kelli swim in still water?