Need help on second part of this question already know first part?

A bank offers to place $500 in an account for 4 yrs. at a rate of 7% compounded twice a year.How much will be?

accumulated at the end of 4 years???

how many more years would it take to accumulate up to $1316.81??

Need help on second part of this question already know first part?tax credit

do you mean how much interest has accumulated at the end of 4 yrs.? If this is the question, you subtract the principal from the answer obtained in the first part.

658. 40 - 500 = 158.40

1316.81 = 500(1.035)^t

log (1316.81) = log (500) + t log (1.035)

[log (1316.81) - log (500)] /log(1.035) = t

28.14881294 years - 4 years = 24.14881294 years more

Need help on second part of this question already know first part?

loan

Since compounding twice a year, the interest rate should be 3.5% every 6-mth.

Using : Amt after nth 6-mth = $500 * ( 1.035)^n,

after 4yr which is the 8th 6-mth, the Amt = 500(1.035)^8 = $658.40

For last part, 1316.81 = 500*(1.035)^n

(1.035)^n = 1316.81/500 = 2.63362

Now taking log on both side,

n lg 1.035 = lg 2.63362

n = lg 2.63362 / lg 1.035 = 28.15 (no. of 6mth) = 14yr 6mth

Since 4yrs have past, he need another 10yr 6mth