Can someone identify the meaning of constant of proportionality?

Fiona and her friends are playing a game by guessing where a coin will land when it is randomly dropped inside the square shown below. fiona guesses that the coin is likely to land in the blue area. which explains whether or not fiona is correct and why?

What is the number 321,000,000 in scientific notation? also what is the number? ?

Interest begins accruing the date of the transaction except for auto loans mortgages credit card cash advances credit card purchases