"Published in Newark, California, USA"
In 1964, Rosario invested a sum of money in the Philippine Catsup Company which gave her a return of ₱ 200 at the end of the year. Had she invested the amount in the Manila Tiles Corporation which declared a dividend of ½ % more, she would have made ₱ 70 more with an investment of ₱ 2,000 less. How much did she invest in the Philippine Catsup Company?
Solution:
The given word problem is about money and investment problem in which the money invested, annual interest rate, and annual income are involved. Let's analyze the given word problem as follows:
Let x = be the amount of money invested at Philippine Catsup Company
y = be the annual interest rate at Philippine Catsup Company
If the word problem says "Rosario invested a sum of money in the Philippine Catsup Company which gave her a return of ₱ 200 at the end of the year.", then the working equation which is her annual income in the said company is
If the word problem says "Had she invested the amount in the Manila Tiles Corporation which declared a dividend of ½ % more, she would have made ₱ 70 more with an investment of ₱ 2,000 less.", then the working equation which is her annual income in the said company is
Next, use the two working equations in order to solve for the value of x and y which are the amount of money invested at Philippine Catsup Company and its annual interest rate, respectively.
But
Hence, the above equation becomes
By using the completing the square method, the value of x which is the amount of money invested at Philippine Catsup Company is
We need to choose the positive sign since we want to get the amount of money invested at Philippine Catsup Company.
The annual interest rate at Philippine Catsup Company is
Therefore, Rosario invested ₱ 20,000 at Philippine Catsup Company with the annual interest rate of 1.0 %.