What is 128 1/5 in simplest radical form

Which of the following is the maximum value of the equation y=-x^2+2x+5 a. 5 b. 6 c. 2. d. 1

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

Iknow the answer but the calculator doesn't seem to give the right one