Tutors Answer Your Questions about Exponential-and-logarithmic-functions (FREE)
Question 930460: Please Help:
The bilious mayor of Duckberg calls the mild mannered young city planner into his office to for a report on the city's projected population growth. The planner explains that the city's population is growing according to P(t)=68,378e^.03t, where t is in years and t= 0 is the present year. The mayor asks how long (in years) that formula predicts it will take to double the city's population. What should the planner answer?
Thank You
Click here to see answer by ewatrrr(24785)   |
Question 930634: A particular drug can be administered via an IV to a patient so that the concentration
of the drug in the bloodstream jumps almost immediately to its highest level. The concentration
then decays exponentially. The half-life of this particular drug is 75 minutes and the effective range
of concentration for the drug in the bloodstream is from 1.5mg/ml to 3mg/ml. If an initial dose
of 100cc of solution containing the drug is given at 2pm, causing the concentration of the drug in
the bloodstream to spike to 3mg/ml. When should the next dose be given? Should the same dose be
given? If not, what percentage of the initial dose should be given?
Click here to see answer by KMST(5328)  |
Question 930450: Please help with the problem:
A satellite has a radioactive isotope for its power supply. The power output in watts after elapsed time t in days since powering up is given by Pt=50e^(-t/2035. The onboard equipment requires 10 watts of power to operate properly. What is the operational life (in years) of the satellite?
Thank You
Click here to see answer by ankor@dixie-net.com(22740)  |
Question 931242: I need help with this problem!
Air pressure at sea level is approximately 14.7 pounds per square inch. The function P(x) = 14.7e^-0.21x models the average atmospheric pressure, P(x) in pounds per square inch, at an altitude of x miles above sea level. Use the model to approximate the atmospheric pressure at the summit of K-2 (28,251 ft). Express your answer in pounds/sq inch rounded to the nearest tenth.
Click here to see answer by rothauserc(4718)  |
Question 931516: In class we learned a lesson on exponential functions, and all the problems we did solved out very easily and evenly. However this paper my teacher gave me has questions that are not as simple as the ones we learned i class, and I have no idea what to do for the last steps.
Problem:
Write an exponential function of the form y=ab^x whose graph passes through the given points.
1. (1,4), (2,12)
Click here to see answer by josgarithmetic(39620) |
Question 931518: Sorry I gave the wrong problem in the previous question I submitted. That was on elf then ash ones I had already done. This one however is on elf the hard ones I can't get.
In class we learned a lesson on exponential functions, and all the problems we did solved out very easily and evenly. However this paper my teacher gave me has questions that are not as simple as the ones we learned i class, and I have no idea what to do for the last steps.
Problem:
Write an exponential function of the form y=ab^x whose graph passes through the given points.
1. (1,3), (2,36)
Click here to see answer by josgarithmetic(39620) |
Question 931525: Please help me solve this problem:
Hiking Staff magazine says that the average hiker experiences a grade of 0.03 or less as flat. The Main Range Trail ascends eastbound out of Yakker's Lake according to H(x)= 0.75+(2/5)Log(x+1), where x is elapsed distance in miles eastbound from the lake, and H(x) is miles above the elevation of the lake.
Mathematics Enthusiast magazine reports that the slope of form
y=C+kLogb(x+1) is k/lnb*(1/x+1)for any positive value of x. In this context, "Grade and "Slope" are synonyms.
Fred an average hiker, hikes eastbound out of Yakker's Lake. How far east of Yakker's Lake does Fred begin to think he is hiking on the flat?
Click here to see answer by KMST(5328) |
Question 933535: A used car has a value of $15,250 when it is purchased in 2012. The value of the car depreciates at a rate of 7.5% per year.
Write an exponential function that models the value of the car, y, over x years.
To the nearest cent, what will be the value of the car after eight years?
Click here to see answer by Theo(13342)  |
Question 934389: I need help solving a problem, i get to a certain point and get stuck.  I get as far as writing the equation in standard formula and the using the quadratic equation but I think that is where I'm messing up and getting stuck.
Click here to see answer by MathTherapy(10552)  |
Question 934219: You want to make an investment in a continuously compounding account earning 1.2% interest. How many years will it take for your investment to double in value? Round the logarithm value to the nearest thousandth. Round the answer to the nearest year.
Click here to see answer by lwsshak3(11628) |
Question 934218: You want to make an investment in a continuously compounding account over a period of 100 years. What interest rate is required for your investment to double in that time period? Round the logarithm value and the answer to the nearest hundredth.
Click here to see answer by lwsshak3(11628) |
Question 934634: (Only a four function calculator can be used)
Radioactive isotope of Iodine is used in many hospitals in medical diagnosis. The isotope decays exponentially over time. The clinic received a shipment of this isotope on 1-16-15. On 1-19-15 there were 100 unites remaining and today 1-21-15, 918 units remain.
a. Write an equation for the relationship between units of isotope and time.
b. How much of the isotope will be left 10 days from today in none used?
c. How long will it take for the number of units to fall below 100 if none is used?
Click here to see answer by josgarithmetic(39620) |
Question 934841: If you have ever swum in a pool and your eyes began to sting and turn red, you are aware of the effects on an incorrect pH level. The pH level measures the concentration of hydronium ions and can be modeled by the function p(t) = –log10 t. The variable t represents the amount of hydronium ions, and p(t) gives the resulting pH level.
Water at 25 degrees Celsius has a pH of 7. Anything that has a pH lower than 7 is called acidic, while a pH above 7 is basic, or alkaline. Seawater has a pH just over 8, while lemonade has a pH of approximately 3.
Create a graph of the pH function. Locate on your graph where the pH value is 0 and where it is 1. You may need to zoom in on your graph.
A pool company forgets to bring their logarithmic charts, but they need to raise the amount of hydronium ions in a pool by 0.50. Using complete sentences, explain how your graph can be used to solve 10–y= 0.50. Find the approximate solution.
The pool company has developed new chemicals that transform the pH scale. Using the pH function p(t) = –log10 t as the parent function, explain which transformation would result in a y-intercept. Use complete sentences and show all translations on your graph.
Click here to see answer by josgarithmetic(39620) |
Question 935307: _____Although there are annual ups and downs, over the long run, growth in the stock market averages about 9% per year. A model that best describes the value of a stock portfolio is probably:
A) linear B)exponential C)logarithmic D)quadratic E)power
*Could you please tell me step by step how to get the answer to the problem? Thank You so much for helping me !! :)
Click here to see answer by josgarithmetic(39620) |
Question 935403: _____Although there are annual ups and downs, over the long run, growth in the stock market averages about 9% per year. A model that best describes the value of a stock portfolio is probably:
A) linear B)exponential C)logarithmic D)quadratic E)power
*Could you please tell me step by step how to get the answer to the problem? Thank You so much for helping me !! :)
Click here to see answer by josgarithmetic(39620) |
Question 935405: _____Five juniors and four seniors have applied for two open student council positions. School administrators have decided to pick the two new members randomly. What is the probability they are both juniors or both seniors ?
A) 0.722 B) 0.395 C) 0.569 D) 0.444 E) 0.506
*Could you please tell me step by step how to get the answer to the problem? Thank You so much for helping me !! :)
Click here to see answer by Edwin McCravy(20059)  |
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