The Knox Valley investment club invested $10,000 at 4.6% annual simple interest. How much additional money should they invest at an annual simple interest rate of 3.5%, so that the total annual interest earned from the two accounts is 4.0% of the total investment?

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)