ᶦᵐ ʲᵘˢᵗ ᵖᵘᵗᵗᶦⁿᵍ ᵃⁿ ᵃᶜᵃᵈᵉᵐᶦᶜ ᵠᵘᵉˢᵗᶦᵒⁿ ᶠᶦʳˢᵗ ˢᵒ ᶦᵗ ᵈᵒᵉˢⁿᵗ ᵍᵉᵗ ᵗᵃᵏᵉⁿ ᵈᵒʷⁿ ᵃⁿʸᵒⁿᵉ ʷᵃⁿⁿᵃ ᵗᵃˡᵏ ᵗʰᵒᵘᵍʰˀ
An element that is unstable and decays of its own accord is .

a metal
a nonmetal
a rare earth element
a radioactive substance

Aswimming pool measures 22ft by 12ft and is 4ft deep. if the pool is being filled at 2.5 cubic ft per minute, how long will it take to fill the pool?

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?

Me d is also an option but i couldn't get it in the picture