Explanation:
32 times or if 84 attempts, that means the relative frequency of tails for friends 1 is
32/84 = 8/21 = 0.380952381... ≈ 0.38
combined they have 3×84 = 252 total attempts. they got together 96 tails.
that relative frequency is
96/252 = 48/126 = 24/63 = 8/21 ≈ 0.38
based on these results we would expect the rehashed frequency for 840 flips to be close to this value 0.38 again.