Maths
posted by Sue .
Please help!!!
The mass of a particular substance is known to grow exponentially at a rate of 1.5% per day. Its initial mass was 230 grams and, after t days, it weighed 325 grams.
The equation modelling this growth is
230×1.015 t = 325.
Use the method of taking logs to solve this equation for t, giving your answer correct to the nearest day.

I think you have a typo, and meant to say ...
230(1.015)^t = 325
(your equation would have a linear growth, not exponentially)
1.015^t = 325/230 = 1.4130435
log(1.015^t) = log 1.4130435
t = log 1.4130435/log 1.015 = 23.222
so it will take appr. 23 days.
Respond to this Question
Similar Questions

Chemistry
Assume that a reaction occurs in which unknown substances R and S react to form unknown substances T and U. From the information below, determine the mass of substance T that will be formed if 45.0 grams of substance R reacts with … 
calculus
assume the halflife of the substance is 31 days and the initial amount is 183.9 grams. (a) Fill in the right hand side of the following equation which expresses the amount A of the substance as a function of time t (the coefficient … 
maths
The mass of a particular substance is known to grow exponentially at a rate of 0.5% per hour. Its initial mass was 25 grams and, after t hours, it weighed 31 grams. The equation modelling this growth is 25×1.005 t = 31. … 
MATH!
The mass of a radioactive substance follows an exponential decay model, with a decay rate of 5% per day. A sample of this radioactive substance was taken six days ago. If the sample has a mass of 3 kg today, find the initial mass of … 
calculus
The rate at which an amount of a radioactive substance decays is modeled by the differential equation dA/dt = kA, where A is the mass in grams, t is the time in years, and k is a constant. Answer the following. a) If a 100gram sample … 
math
Kittens weigh about 100 grams when born and gain 7 to 15 grams per day. If a kitten weighed 100 grams at birth and gained 8 grams per day, in how many days will the kitten triple its weight? 
Chemistry Help Please!!!
A radioactive substance has a halflife of 4 days. Suppose we have 800 mg of this substance. a) Find the equation of the mass remaining after t days. Use the exact value for k not a decimal approximation. b) Rounding your answer to … 
Calculus Help Please!!!
A radioactive substance has a halflife of 4 days. Suppose we have 800 mg of this substance. a) Find the equation of the mass remaining after t days. Use the exact value for k not a decimal approximation. b) Rounding your answer to … 
Algebra  Can you PLEASE check  I"m stuck!
Bob is studying the growth of a particular species of plant. He writes the following equation to show the height of the plant f(n), in cm, after n days: F(N)=10(1.02)^n 1. Starting from 0 days, plug xvalues into our function to find … 
Exponential Modeling
The halflife of a radioactive substance is one day, meaning that every day half of the substance has decayed. Suppose you have 100 grams of this substance. How many grams of the substance would be left after a week?