Drake is comparing time people spend playing games on xbox versus playstation. in his study, individuals ages 10 - 15 are given xbox's and individuals ages 16 - 25 are given playstations. after collecting his data he observes that those using the playstation had logged more hours. drake concludes that the playstation is more popular. this is an example of :
a. experimental bias
b. skepticism
c. controlled environment
d. a qualitative observation
two 8th grade students decided to race around the track at their school. one had running shoes on and the other student was wearing sandals. their running speed was compared. what is the dependent variable?
a. types of shoes
b. age of the students
c. speed of the students
d. distance the students ran

The correct answer will be option-

1. Option-A

2. Option-C

Explanation:

Case I

The researcher wants to study and compare the time spent by the people on games on Xbox and Play stations.

His experiment included the people of the age of 10 - 15 and 16 - 25 years by providing  Xbox's to the people of 10 - 15  years and Play-stations to the 16 - 25 years.  

This is a case of experimental bias as his investigation was a comparative analytical investigation which should be performed between the same group and the independent variable provided should also be the same Also it lacked the control group.

Thus, option-A is the correct answer.

Case II

In the given case, the researcher compared the speed of two 8th grade students by providing running shoes to one student and sandals to another.

This experimental design included the dependent variable as the speed of the students as the speed is the variable which is being tested in the experiment.

Thus, option-C is the correct answer.

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.