Suppose you invest $10000 at 5.1% annual interest, compounded weekly. How long will it take to double your money? Round to the nearest year. (Hint this will be a whole number)
Q. Suppose you invest $10000 at 5.1% annual interest, compounded weekly. How long will it take to double your money? Round to the nearest year. (Hint this will be a whole number)
Identify formula for compound interest: Identify the formula to use for compound interest.The formula for compound interest is A=P(1+nr)nt, where:A is the amount of money accumulated after n years, including interest.P is the principal amount (the initial amount of money).r is the annual interest rate (decimal).n is the number of times that interest is compounded per year.t is the time the money is invested for in years.We want to find t when A is double the principal P.
Set up equation with given values: Set up the equation with the given values.We know that A=2P (since we want to double the money), P=$10,000, r=5.1% or 0.051 (as a decimal), and n=52 (since interest is compounded weekly).So, the equation becomes 2P=P(1+0.051/52)52t.
Simplify the equation: Simplify the equation.We can divide both sides by P to get 2=(1+0.051/52)52t.
Solve for t: Solve for t.To solve for t, we need to take the natural logarithm (ln) of both sides:ln(2)=ln((1+0.051/52)52t).Using the power rule of logarithms, we get:ln(2)=52t⋅ln(1+0.051/52).
Isolate t: Isolate t.Divide both sides by 52×ln(1+0.051/52) to get:t=52×ln(1+0.051/52)ln(2).
Calculate value of t: Calculate the value of t.Using a calculator, we find:t≈52×ln(1+0.051/52)ln(2).t≈52×ln(1.00098039216)0.69314718056.t≈52×0.000980198020.69314718056.t≈0.050970296040.69314718056.t≈13.60546875.
Round answer to nearest year: Round the answer to the nearest year.Since we are asked to round to the nearest year, t≈14 years.
More problems from Exponential growth and decay: word problems