Question

Donnesh puts $5,000 into a savings account with a 10% interest rate. How long will it take to double the initial amount?

Answer 1

Do you know whether they want simple or compound interest?

Answer 2

old question, answering to close

for simple interest, A = P + Prt where A is the final amount, P is the principal (5000), r is the interest rate as a decimal (0.10), and t is time. since you're looking to double the investment, A = 2P. substitute, plug in the appropriate values, evaluate t.

for compound interest, A = P(1+r)^t, same principle, plug in and solve for t.