Jed deposited $400 into a bank that offers 3.9% interest rate compounded daily and how many years will his balance be $800

18 years (approx)

Step-by-step explanation:

Since, if an amount is compounded daily,

Then, the final amount after t years is,

A = P (1 + r/365) 365t

Where, P is the principal amount

r is the annual rate (in decimals),

t is the number of years,

Given,

A = $ 800,

r = 3.9% = 0.039,

P = $ 400,

By substituting the values,

800 = 400 (1 + 0.039/365) 365t

t = 17.774 = 18

Hence, his balance will be $800 after approximately 18 years.