3.375. There are 16 different ways you can flip four coins. 1/16 of them are HHHH and TTTT, 4/16 are one T and three H, 4/16 are one H and three T, and 6/16 are two H and two T. If we can flip two or four tails at any point then all the cases with 2 T and 2 H become 4 H and the cases with 3T and 1 H become 3 H and one T and the cases with 4 T become 2 T and 2 H. So we expect 7/16 (4) +8/16(3)and 1/16(2)=3.375.

3.25. There are 16 different ways you can flip four coins. 1/16 of them are HHHH and TTTT, 4/16 are one T and three H, 4/16 are one H and three T, and 6/16 are two H and two T. If we can flip two or four tails at any point then all the cases with 2 T and 2 H become 4 H and the cases with 3T and 1 H become 3 H and one T and the cases with 4 T become 2 T and 2 H. So we expect 7/16 (4) +8/16(3)and 1/16(2)=3.375.