How quickly can you raise your Hostelworld ratings? (spreadsheet)

I've been experimenting with a spreadsheet to see how quickly a hostel can improve its Hostelworld ratings.

Here's an example of one way to do it, using as an example a hypothetical hostel that has 150 reviews with an average rating of 80%:

(NOTE: I'm using OpenOffice -- Excel might have slightly different commands.)

• Highlight 150 rows in column A of the spreadsheet.
• Right click on the highlighted rows and format the cells as "percent"
• Put 80% into one cell, then copy it and "paste special" into all 150 cells to get 80% value in every highlighted cell.
• Highlight rows 1 to 150 in column B and format as a percent
• In another cell off to the side, for example E3, enter the formula =AVERAGE(A1:B150). Cell E3 will now contain your current Hostelworld rating based on your 150 reviews.

Column A: your current 150 reviews which average 80%
Column B: you can add up to 150 new reviews in this column to see how many you need to bring your average rating up

Here's what happens when you add fifteen 100% reviews to a hostel with 150 reviews averaging 80% -- the total rating goes up to 81.82%, not very much:

Also take into account that old Hostelworld reviews expire in 6 months, so if you add fifteen 100% reviews, you might be able to subtract fifteen 80% reviews. The average is still basically the same though (82%) unless your oldest reviews have a lower average than 80%. (The number of old reviews you can subtract is probably related to the season it was 6 months ago -- if it was low season then and high season now, you can add more reviews in proportion to the number subtracted.)

I hope that makes sense :D