First, you have to calculate the amount of tuition when the student reaches age 18. Do this by multiplying $11,000 by 1.07 each year from age 12 until it reaches age 18. Thus, 7 times.
At age 18: 16,508
At age 19: 17,664
At age 20: 18,900
At age 21: 20,223
Then, we use this formula:
A = F { i/{[(1+i)^n] - 1}}
where A is the monthly deposit each year, F is the half amount of the tuition each year illustrated in the first part of this solution, n is the number of years lapsed.
At age 18:
A = (16508/2) { 0.04/{[(1+0.04)^6] - 1}} = $1,244.389 deposit for the 1st year
Ate age 19
A = (17664/2) { 0.04/{[(1+0.04)^7] = $1,118 deposit for the 2nd year
At age 20:
A = (18900/2) { 0.04/{[(1+0.04)^8] = $1,025 deposit for the 3rd year
At age 21:
A = (18900/2) { 0.04/{[(1+0.04)^8] = $955 deposit for the 4th year
