Alena and Estella can complete a job in 18 hours when they work together. If they invite Tommy to help, how long will the job take? How many friends need to
work together on the job to complete it in 4 hours

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?

Anyone know? will mark brainliest if correct!

Twelve different video games showing substance use were observed and the duration times of game play (in seconds) are listed below. the design of the study justifies the assumption that the sample can be treated as a simple random sample. use the data to construct a 99% confidence interval estimate of μ, the mean duration of game play. 4028 4316 4816 4650 4036 5010 4833 4331 4307