12. Callahan (2009) demonstrated that tai chi can signifi- cantly reduce symptoms for individuals with arthritis.
Participants were 18 years old or older with doctor-
diagnosed arthritis. Self-reports of pain and stiffness
were measured at the beginning of an eight-week tai
chi course and again at the end. Suppose that the data
produced an average decrease in pain and stiffness of
Mp = 8.5 points with a standard deviation of 21.5 for
a sample of n = 40 participants.
a. Use a two-tailed test with a = .05 to determine
whether the tai chi had a significant effect on pain
and stiffness.
b. Compute Cohen's d to measure the size of the
treatment effect.

step-by-step explanation:

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

b

step-by-step explanation:

it have 5 sides and 5 identicle angle.the rest does not have the same property as b.

brainliest

a

step-by-step explanation:

u take $30 minus $24. the answer/original($30)