The first couple of questions on that screenshot

11. If the balance in the account in problem #10 is $1200 initially, what is the balance in 15 years? (5 points) 12. The half-life of a radioactive isotope is 450 years. If you start with 100 g of the substance a) what fraction remains in 900 years? (3 points) b) How many grams remain after 75 years? (4 points) I 13. Conservation efforts led to increase of the population of East Asian tigers with projected doubling of the population between years 2010 and 2022. If there were 3200 tigers in East Asia in 2010, how many tigers there are today (take the end of 2017 as "today")? (4 points) 9. On an 8 X 8 chess board, there are 64 squares. If one penny is placed on the first squire, two on the second square, four on the third square, 8 on the fourth square, and so on, how many pennies are there on the 13th square? 6 points) I 10. The doubling time of a bank account balance is 22 years. By what factor does it grow in 60 years? (5 points)