How to calculate the content of green grid? Thank you

12. After saving diligently throughout your entire career, you and your spouse are finally ready to retire with a nest egg of $1,000,000. You need to invest this money in a mix of stock and bonds that will allow you to withdraw $7,000 per month for 25 years. What annual interest rate do you need to earn? This problem is similar to Example 5-8 on page 162. 25 Amount available to invest at retirement $1,000,000 Amount needed per month $7,000 Years of monthly income needed Months in a year 12 Months of monthly income needed 300 Solution: 300 Monthly interest rate needed (RATE) Solution: 0.57% Annual interest rate needed Solution: 6.89% How could you ensure that the retirement nest egg will last greater than 25 years