half yearly revision

In the half yearly exam only 70% if the students were passed. Out of these (passed in half yearly) only 60% student are passed in annual exam. Out of those who did not pass the half yearly exam, 80% passed in annual exam. What per cent of the students passed the annual exam ?

For calculation of interest compounded half yearly, keeping the principal same, which one of the following is true.

Rs 1600 lent at a compound interest of 5% per annum, compounded half yearly for one year will amount to:

When the interest is compounded half yearly, the number of conversion periods in a year is four.