Final answer:
Cody is following the investment practice of investing in stocks, but he should diversify his portfolio to improve it. If he puts his money in an account with 5% interest, his money would double in around 14 years.
Step-by-step explanation:
Cody is following the investment practice of investing in stocks. However, he has failed to avoid the investment shortcoming of not diversifying his portfolio. To improve his investment portfolio, Cody should consider diversifying his investments by investing in different types of assets such as bonds, real estate, or mutual funds. If Cody sold all his stocks and put the total amount in an account with 5% interest, his money would double in approximately 14 years.