Final answer:
The question seems to be related to historical events, specifically the Constitutional Convention of 1787, but the provided information does not detail a decision to raise the number of official delegates to 475.
Step-by-step explanation:
The question refers to the Constitutional Convention that took place in Philadelphia in 1787. This gathering was originally intended to revise the Articles of Confederation but ultimately resulted in the creation of a new government and the drafting of the United States Constitution. Among the delegates were notable figures such as George Washington, James Madison, and Benjamin Franklin. No record of a vote to raise the number of official delegates to 475 exists in this context; the information provided does not fully answer the initial question but it is clear that it pertains to the events surrounding the Constitutional Convention.