Enter 7. Find the function y =f(x) which passes through (0, 10) and has dy dx 4V. 8. Determine the principal P that must be invested at interest rate r = 6% compounded monthly so that $500 000 will be available for retirement in 40 years. 9 . The number of a certain type of bacteria increases continuously at a rate proportional to the number present. If there are 100 present at a certain time and 300 present 5 hours later, how many will there be 10 hours after the initial time? How long does it take for the number of bacteria to double? 10. When an object is removed from a furnace at 1500 F to a room at 90 F, its temperature drops to 1120 F in one hour. Find the temperature five hours after the removal