Which of the following statements contain a variable? check all that apply.

a. half the speed of the car.
b. they scored 27 points.
c. eighty miles per hour.
d. the number of different colors on the page.

Aresearcher believes increased perceived control influence the well-being of residents at a nursing home. to test this , she allowed one group of residents to have control over their daily lies, (where to eat etc) . the other group of 5 residents had these deceisions made by staff. the resident's feelings of well-being were measured on a 10 point scale at the end of a one month trial period. is there a difference on well-being?