According to how the other half lives, where did the only fresh air for tenement rooms come from?

In 1990, the average income for an american worker was $1,518 per month. in 2000, the average income for an american worker was $2,632 per month. during this time period, a basket of necessities (food, housing, etc.) increased from $657 per month in 1990 to $1,402 per month in 2000. the real value of income ▼ increased decreased over that 10-year period.

The principle that the geoglical processes that we see today have occurred through out earths history is called

Dr. redbull conducts a study to determine whether her new energy drink children perform better on spelling tests. she randomly assigns children to one of two groups: group 1 receives her energy drink and group 2 receives water. she then gives both groups a spelling test and compares the results. which of the following is true about this study? a. group 1 is the dependent variable and group 2 is the independent variable. b. this is a correlational study. c. group 2 is the experimental group. d. the independent variable is the type of drink the children receive.