7. 3.61 Royalties paid to holders of mineral rights tend to decrease with time as resources become depleted. In one particular case, the rights holder received a royalty check of $18,000 six months after the lease was signed. She continued to receive checks at 6-month intervals, but the amount decreased by $2000 each time. At an interest rate of 10%

per year compounded semiannually, the equivalent uniform semiannual worth of the royalty payments through the first 4 years is closest to:

1. $11,511 2. $15,352 3. $19,236 4. $24,489