This is an interesting question.
It says that each patient needs individual care. So this means one nurse can't care for multiple patients.
Let's first find out how many patients a nurse can care for on their shift.
If they work for 12 hours, and each patient needs 4 hours of care, that they can care for 12/4, or 3 patients on their shift.
I'm thinking you can't have a nurse work back-to-back shifts and thus care for 6 patients in a 24 hour period. If you could do this you would get a different answer.
Anyway, if one nurse can care for 3 patients and there are 17 patients, that means that 17/3 tells us how many nurses we need.
$$\frac{17}{3} = 5\frac{2}{3}$$
Of course, you can't have a 2/3 ofa nurse, so you would round up and need 6 nurses.
