These types of deposits are very common in the business world, where small and large businesses deposit regular or irregular amounts of money into mutual funds or many other investment accounts.
The purpose, in this example, is to find the interest rate that these funds earned in 2015. This interest rate is called IRR, or Internal Rate of Return.
Many softwares are available to calculate such returns, including many spreadsheets such as Excel to calculate these returns. I happened to have software programmed into my computer to do these calculation very rapidly.
All these softwares do the same thing, which is to find the PV of all these payments which will equate them to the final market value of the fund, which in this case is $112,500. So, they use iteration to find a couple of interest rates, and then use interpolation between them to arrive at actual IRR. This is what Wolfram/Alpha does.
Now, entering these amounts into my computer, it comes out with a daily rate of=.00057492740959, which is essentially the same as Melody found using Wolfram/Alpha engine. The custom, in the business world, is to raise this number to the power of 365 days to find the Effective IRR.
So, 1.00057492740959^365=23.34%, which is basically the same as Melody found.