On Juan's 26th birthday, he deposited $9,000 in a retirement account. Each year thereafter, he deposited $1,000 more than the previous year. Using a gradient series factor, determine how much was in the account immediately after his 35th deposit if:
a. the account earned annual compound interest of 6.0%. Round entry to the nearest dollar. The tolerance is ±4.
b. the account earned annual compound interest of 7.0%. Round entry to the nearest dollar. The tolerance is ±4.