X P(x) 0 0.25
1 0.3
2 0.25
3 0.2

Required:
Find the standard deviation of this probability distribution.

Tim's phone service charges $23.06 plus an additional $0.22 for each text message sent per month. if tim's phone bill was $28.56, which equation could be used to find how many text messages, x, tim sent last month?

10 ! in a race, nick is 50 feet in front of jay after ten seconds. how fast can nick run, if jay can run 20 feet per second?

Find the domain of the following expression: 1/(√x)-2