11. When two musical notes are a "fourth" apart, the frequency of the lower note is the frequency of the higher note. Using f as the frequency of the higher note, write an expression for the frequency of the lower note.

Abank manager wants to encourage new customers to open accounts with principals of at least $2 comma 500. he decides to make a poster advertising a simple interest rate of 3%. what must the principal be if the bank manager also wants to advertise that one can earn $10 the first month? can the poster correctly say, "open an account of $2 comma 500 and earn at least $10 interest in 1 month! "?