Helene invested a total of $1,300 in two simple interest bank accounts. One account paid 7% annual interest; the other paid 8% annual interest. The total amount of interest she earned after one year was
$100. Enter and solve a system of equations to find the amount invested in each account. Enter the
interest rates in order as given in the problem. (Hint: Change the interest rates into decimals first.)
(*
X +
y =
Helene invested $
at 7% and $
at 8%.

Ascientist places 24 cells in a petri dish. she knows the cells grow at an exponential rate, doubling in number every hour. how long will it take (in hours) for there to be 1100 cells in the dish? time to 1100 cells: 5.51832530 hours how long will it take to reach 110 cells? time to 110 cells : 2.1963972 hours what is the average rate of change in the number of cells between 9 hours and 11 hours? average rate of change: cells per hour what is the instantaneous rate of change after 7 hours? instantaneous rate of change: cells per hour note: you can earn partial credit on this problem.