Mike's grandmother opened a savings account in mike's name and deposited some money into the account. the account pays an annual simple interest rate of 7%. after 14 years, the interest earned on the account was $6,860. how much money did mike's grandmother deposit in the account? a. $7,500 b. $8,000 c. $7,000 d. $6,000

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)