To estimate the difference we need four averages for the categorized groups i. e., control group before change, control group after change, treatment group before change and treatment group after change. a. True
b. False

b. False

Step-by-step explanation:

In a research study, when a researcher wants to find the impact of a new treatment, then the researcher randomly divides the the study participants into two groups. The groups are :

-- control group

-- treatment group

The control group is a group that is used to establish the cause-and-effect relationship by making the effect of an independent variable isolate. It receives no treatment or some standard treatment for the which the effect is already known.

The treatment group receives the treatment for which the effect the researcher is interested in.

Thus the averages of the four categorized groups are not required for estimating the difference.

Therefore, the answer is FALSE.

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm

true

step-by-step explanation: