4. (10 pts) A study is conducted to estimate the difference in the mean occupational exposure to radioactivity in computer science students in the years 2000 and 2008. These data based on independent samples of students for the 2 years are obtained:

Select all the correct answers. what is 221,000,000,000,000,000,000 expressed in scientific notation?

Imogene invested $8,000 in a bank account that pays 8 percent simple interest at the end of each year. her friend invested the same amount in stocks where the growth of the investment is represented as 2,000 times the square root of 2 less than the time lapsed in years. if y1 and y2 represent the amount earned in dollars and t is the time lapsed in years, which system of equations correctly represents the situation?

Select the sequences that are geometric.