How to calculate average age?

When the FAI announced the starting XI against Latvia, the average age of the starting XI was stated as being 23.6, but in the announcement from the @irish_abroad account stated the average age was 24, see below

STARTING XI | Ireland v Latvia Evan Ferguson makes his first senior international start as Caoimhin Kelleher starts in goal in young, exciting starting line-up🧤 Average age of the side: 23.6 💚 pic.twitter.com/axVsxKuYlx — Ireland Football ⚽️🇮🇪 (@IrelandFootball) March 22, 2023

📋 Starting XI Stats 🎂 Average Age: 24 🧢 Total Caps: 151 🧢 Average Caps: 14.73 ⚽ Total Goals: 9 ⚽ Average Goals: 0.82#COYBIG #IRLLAThttps://t.co/4YfyHGMIIc pic.twitter.com/j2EMe16jWr — Irish Abroad (@irish_abroad) March 22, 2023

Why is there a discrepancy? The team running the FAI social media channels calculated the age using each player's years of age, e.g. Alan Browne is 27, but this is inaccurate. Browne is 27 years and 11 months old.

When calculating average age, it's better to use the days between each person's date of birth and the current date - Browne was 10,203 days old on Wednesday, 22nd March 2023. Calculating the age in days for the rest of the team that started against Latvia gives the following table

Player	Date of birth	Age(y)	Age(days)
Caoimhin Kelleher	Monday, 23 November 1998	24	8,885
Andrew Omobamidele	Sunday, 23 June 2002	20	7,577
Matt Doherty	Thursday, 16 January 1992	31	11,388
Alan Browne	Saturday, 15 April 1995	27	10,203
Dara O'Shea	Thursday, 4 March 1999	24	8,784
Jay Molumby	Friday, 6 August 1999	23	8,629
Michael Obafemi	Thursday, 6 July 2000	22	8,294
Will Smallbone	Monday, 21 February 2000	23	8,430
Callum O'Dowda	Sunday, 23 April 1995	27	10,195
Nathan Collins	Monday, 30 April 2001	21	7,996
Evan Ferguson	Tuesday, 19 October 2004	18	6,728
	Total	260	97,109
	Average	23.64	8,828.09

To convert the average age in days to years, divide by the number of days in a year, including a quarter for leap years, i.e. 365.25.

This gives a more accurate average age of 24.17 days.