60% pass the test first time. Of the 40% that fail, 80% pass on the second attempt, so that's 0.4×0.8=0.32=32%. The probability of passing on the second attempt is therefore 32%.
If we take 1000 examinees as the start:
1st attempt: 600 pass, 400 fail (60% of 1000 pass)
2nd attempt: 320 pass, 80 fail (80% pass of the 400 who failed before)
3rd attempt: 72 pass, 8 fail (90% pass of the 80 who failed)