these are deferred Annuities questions,i posted some formula too

SH Enterprises needs to borrow to finance a project. No payments are to be made during the development period of 3 years (over which time, the loan still accumulates interest). Then repayment of the loan involves payments of $8628 at the end of every three months for 10 years. Interest is 6.6% compounded quarterly. Determine the total amount of interest charged. Answer: Best Buy has a plan where you don't begin payments for 23 months. You then begin payments of $277 at the beginning of every month for 19 months. Assume the interest rate is 3% compounded monthly over the whole time interval (even when you don't have any payments). What was the value of the home theatre set at the time of purchase? Answer: Month end contributions of $498 are made to an account for 9 years. For exactly 9 years following the date of the final payment the funds are allowed to accumulate interest. After this time, start of quarter withdrawals are made for a period of 8 years. If the interest rate over the entire 26 year period is 3.2% compounded quarterly, then what is the maximum amount that can be withdrawn at the start of each quarter? Answer: Helpful Forumulas (Cont'd): Annuities ieff=(1+i)f1i2=(1+i1)f1/f21FV=PMT[i(1+i)n1]PV=PMT[i1(1+i)n]n=ln(1+i)ln(1+iPMTFV)n=ln(1+i)ln(1iPMTPV)PVperp=iPMTieff=er1i2=er//r1r=f1ln(1+i1)FVdue=PMT[i(1+i)n1](1+i)PVdue=PMT[i1(1+i)n](1+i)n=ln(1+i)ln(1+iPMT(1+i)FVduc)n=ln(1+i)ln(1iPMT(1+i)PVV0)PVPerpdue=iPMT+PMT