终于做出来了，答案和已有的不太一样

Step 0:
(1, 1, 1, 1, 1)

Step 1:
two mice eat first cake, and one mouse eat second cake and one mouse eat third cake, after 30 minutes
(0,1/2,1/2,1,1)

Step 2:
three mice eat the rest of the second cake, and one mouse eat the fourth cake, after 10 minutes
(0,0,1/2,5/6,1)

Step 3:
one mouse eat the rest of the fourth cake, and one mouse eat fifth cake, after 50 minutes
(0,0,1/2,0,1/6)

Step 4:
4 mice eat the rest of third cake, that is 7.5 minutes

Step 5
5 mice eat the rest of fifth cake, that is 2 minutes

Step 4+step 5=9.5 minutes