7:34 PM Sat Oct 15 4 '11' 98% - webassignnet ri Need Help? 43. [0/056 Points] PREVIOUS ANSWERS SPRECALC7 4.5.098.Ml. 1/5 Submissions Used ASK YOUR TEACHER Environmental scientists measure the intensity of light at various depths in a lake to find the "transparency" of the water. Certain levels of transparency are required for the biodiversity of the submerged macrophyte population. In a certain lake the intensity of light at depth x is given by I = 250.003x where I is measured in lumens and x in feet. (a) Find the intensity I at a depth of 15 ft. (Round your answer to two decimal places.) S x lumens (b) At what depth has the light intensity dropped to I = 1? (Round your answer to one decimal place') :JX it Need Help? Submit Answer Submit Assignment Save Assignment Progress 21. [0.1/0.32 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.5.001. i/S Submissions Used Let's solve the exponential equation 3eX : 45. (a) First, we isolate ex to get the equivalent equation (b) Next, we take In of each side to get the equivalent equation (c) Now we use a calculator to find x zl X . (Round your answer to three decimal places.) Need Help? _' Submit Answer (35:15 X MY NOTES ASK YOUR TEACHER 17. [-/0.32 Points] DETAILS SPRECALC7 4.4.058.MI. 0/5 Submissions Used MY NOTES ASK YOUR TEACHER Use the Laws of Logarithms to combine the expression. loga(b) + cloga(d) - r loga(s) Need Help? Read It Master It14. [0/0.32 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.4.515.XP.MI. 1/5 Submissions Used MY NOTES ASK YOUR TEACHER Use the Laws of Logarithms to combine the expression. log(81) + = log(2) - log(9) X Need Help? Read It Master It Submit Answer 15. [0/0.32 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.4.054.MI. 1/5 Submissions Used MY NOTES ASK YOUR TEACHER Use the Laws of Logarithms to combine the expression. 1092 ( x2 - 4) - 1092 ( x - 2) X Need Help? Read It Master It42. [010.32 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.5.090.M|. 1/5 Submissions Used MY NOTES ASK YOUR TEACHER A woman invests $5500 in an account that pays 6% interest per year, compounded continuously. (a) What is the amount after 2 years? (Round your answer to the nearest cent.) $ :1 x (b) How long will it take for the amount to be 510,000? (Round your answer to two decimal places.) x Yr Need Help? Submit Answer 20. [0.161032 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.4.074.M|. 1/5 Submissions Used Some biologists model the number of species Sin a fixed area A (such as an island) by the species-area relationship log(S) = Iog(c) + k log(A) S: -~' where c and k are positive constants that depend on the type of species and habitat. (a) Solve the equation for S. X (b) Using part (a), if k = 2 and the area is tripled, then by what magnitude is the number of species increased? Need new MY NOTES ASK YOUR TEACHER Submit Answer 19. [0/0.32 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.4.070.MI. 1/5 Submissions Used MY NOTES ASK YOUR TEACHER Simplify: (log7(3))(log3(8)). X Need Help? Read It Watch It Master It Submit Answer7:48PM SatOctlS 4993%_. webassignnel i Solve the logarithmic equation for x, as in Example 7. (Enter your answers as a commaseparated list.) log5(6) + logs(x) = logs(8) + logs(x 5) X: 20 y Need Help? 35. [0/032 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.5.051.M|. 3/5 Submissions Used MY NOTES ASK YOUR TEACHER Solve the logarithmic equation for x, as in Example 7. (Enter your answers as a commaseparated list.) 2 |og(X) = log(2) + log(6x a 10) Need Help? 37. [032/032 Points] DETAILS PREVIOUS ANSWERS SPRECALC7 4.5.087.M|. 1/5 Submissions Used MY NOTES ASK YOUR TEACHER Find the value(s) of x for which the equation is true. log(x + 9) : log(x) + log(9) x=- Need Help? 38. [/0.32 Points] DETAILS SPRECALC7 4.5.088.Ml. 0/5 Submissions Used MY NOTES ASK YOUR TEACHER Find the value(s) of x for which the equation is true. (Round your answers to four decimal places.) 00900)3 = 3 |09(X) X = C] (smallest value) x