I think you forgot about the "front-end" deposits made in years 2 and 3....
At the end of the first year, the account is worth ... (10,000)(1.1) = $11, 000
At the start of the second year....he deposits $10,000 more dollars.....so the account is worth (11000 + 10000)(1.1) = $23,100 at the end of the second year.
At the start of the 3rd year $10,000 is added to this, so the account balance at the end of the third year is just(23,100 + 10000)(1.1) = $36,410
