Final answer:
The assertion about estimating monthly income by doubling it to reach approximately $900 is false, and after examining Mary Ann's budget, it is determined that she can save 10% of her after-tax monthly income with her current expenses.
Step-by-step explanation:
The original question about estimating monthly income by simply multiplying it by 2 for a total of approximately $900 is false.
Now, let's consider Mary Ann's financial scenario. Mary's after-tax monthly income is $2,589.10, and she aims to save 10% of this amount. To determine if saving 10% is feasible given her expenses, we need to calculate her total monthly expenses and subtract it from her income. Her expenses including rent, cell phone, utilities, cable TV and internet, groceries, entertainment, car payment, and gasoline sum up to $2,145. Therefore, Mary Ann can indeed save 10% of her income, as her expenses are less than her monthly income. After subtracting her total expenses from her monthly income, Mary Ann would have $444.10 left, which is more than the $258.91 (10% of her income) she wants to save.