Who is the leading allrounder in T20Is?

Is Mujeeb Ur Rahman the youngest overseas player to feature in the IPL? asked Qadir Ahmed from Pakistan
The Afghanistan spinner Mujeeb Ur Rahman was born on March 28, 2001, and so was only 11 days past his 17th birthday when he made his debut for Kings XI Punjab against Delhi Daredevils in Chandigarh on April 8 this year. That doesn't just make him the youngest overseas player in the IPL (a record formerly held by the Australian allrounder Mitchell Marsh, at 18 years 170 days in 2010), but the youngest from anywhere.

Mujeeb took the overall record from Sarfaraz Khan, who was aged 17 years 177 days when he made his IPL debut, for Royal Challengers Bangalore against Chennai Super Kings in Bengaluru in 2015. Four other 17-year-olds have appeared in the IPL: Pradeep Sangwan (for Delhi Daredevils in 2008), Washington Sundar and Rahul Chahar (both for Rising Pune Supergiant in 2017), and Ishan Kishan (Gujarat Lions 2016).

The oldest man to appear in the IPL is the Australian spinner Brad Hogg, who was 45 years 92 days old when he played his last match for Kolkata Knight Riders in 2016. Praveen Tambe (43), Muttiah Muralitharan (42), Shane Warne and Adam Gilchrist (41), Sanath Jayasuriya, Rahul Dravid, Azhar Mahmood and Sachin Tendulkar (40) all played when they were over 40 years of age. Tendulkar's last IPL match, in Mumbai in 2013, came 19 days after his 40th birthday.

Is it true that Frank Worrell's batting average never went below 50 until his final Test? asked Craig Lewis from Barbados
The great West Indian batsman Sir Frank Worrell played 51 Tests, and finished with a batting average of 49.48 after being bowled by Brian Statham for 9 in his final match, at The Oval in 1963. Before that his average had been 50.01.

After his first two Tests - against England in 1947-48 - brought innings of 97, 28 not out and 131 not out, Worrell had an average of 256. Not surprisingly it dropped a little after that, but it was still over 70 after 14 matches (by the end of West Indies' tour of Australia and New Zealand in 1951-52). It remained over 50 almost throughout the rest of his career - but did dip just below that during the first two matches of India's tour of the Caribbean in 1961-62. A duck in the first Test, in Port-of-Spain, took him to a career-low 49.79. An innings of 58 in the next Test took it back to 49.91, then 77 in Bridgetown got the average back above 50, where it stayed until his final Test, by which time Worrell was 39. For his averages throughout his Test career, click here.

The only two players who maintained a batting average of over 50 throughout their Test careers were Herbert Sutcliffe of England, whose lowest was his final mark of 60.73, and Pakistan's Javed Miandad (a lowest of 51.75).

Was Australia's 209 the other day the highest total in a women's T20 international? asked Jamie Stewart from Canada
Australia's 209 for 4 against England in Mumbai last month was indeed the highest score in women's T20Is. The only other total above 200 is South Africa's 205 for 1 against the Netherlands in Potchefstroom in October 2010. Then comes England's 199 for 3, to overhaul India's 198 for 4 in Mumbai last month (six days before Australia's record). Not surprisingly, that match, which featured 397 runs in all, had the highest aggregate for any women's T20I.

I wondered who the leading allrounder was in men's T20 internationals - has anyone yet scored 500 runs and taken 50 wickets? asked David Powell from England
At the moment there are six men who have reached both 500 runs and 50 wickets in T20Is. The man nearest to the 1000-run/100-wicket double is Shahid Afridi: he's the leading wicket-taker overall, with 97, and also scored 1405 runs - but he played the last of his 98 matches in March 2016.

The others to have done it are Dwayne Bravo of West Indies (1142 runs and 52 wickets), Mohammad Nabi of Afghanistan (961 runs and 61 wickets), Ireland's Kevin O'Brien (702 runs and 54 wickets), Thisara Perera of Sri Lanka (959 runs and 50 wickets), and Bangladesh's Shakib Al Hasan (1237 runs and 75 wickets)

Will the ECB's new 100-ball competition require a whole new set of statistical records? asked Martin Sanders from England
I imagine it will: I can almost see some of the technical boffins in ESPNcricinfo's offices scratching their heads about it even now, especially how to cope with the idea of a ten-ball over. (Bowlers everywhere are presumably doing the same.)

I suppose it might be possible to lump the figures together with the T20 ones, perhaps calling it "short-form" or some similar name. The existing List A figures, after all, include matches played over a variety of innings lengths. In England alone there have been regular competitions over 40, 45, 50, 55 and 60 overs (and even 65 in the earliest days of the Gillette Cup), and all these are treated as one format for stats purposes.