We want to perform the "experiment" 25 times, expecting 6 "failures" and 19 "successes", knowing that we have a 0.6 success probability. The binomial distribution states that this happens with probability
[tex]\displaystyle P(X=19)=\binom{25}{19}(0.6)^{19}(0.4)^6=0.0442[/tex]
i.e. a 4% chance.
It would be very surprising if all 25 did not use foil as their main weapon, because we expect about 60% of fencers using it, which is more than half.