Throuput Accounting

Hi Sir/Madam,
I have just done a question on the study book of BPP (2017 version, page 466) about the thoughput accounting. Here is the question:
F Co makes and sells two products, A and B, each of which passes through the same automated production operations. The following estimated information is available for period 1.
Product unit data

Direct material cost of A and B are $2 and $40 respectively
Variable production overhead cost ($) of A and B are $28 and $4 respectively
Original estimates of production/sales of products A and B are 120,000 units and 45,000 units respectively. The selling prices per unit for A and B are $60 and $70 respectively.

Maximum demand for each product is 20% above the estimated sales levels.
Total fixed production overhead cost is $1,470,000. This is absorbed by products A and B at an average rate per hour based on the estimated production levels.

One of the production operations has a maximum capacity of 3,075 hours which has been identified as a bottleneck, limiting the overall estimated production/sales of products A and B. The bottleneck hours required per product unit for products A and B are 0.02 and 0.015 respectively

Required:

If F Co choose to prioritise the manufacture of Product A, calculate the value (in $) of the maximum net profit using throughput analysis.

The result that I find out is $ 3,188,000. But the answer of BPP is $ 3,732,000. The reason for different in my result is due to the production levels I used to calculate the overhead cost. I used the production level to maximise the profit, but BPP used the production level of estimated production/sales (120,000 and 45,000). Can you help me to explain why uses the estimated production here.

Thank you so much for any helping from teacher and other people!