Class 8 try these chapter 8 page number 130

Time Period When Compounded Half Yearly = n x 2
Rate When Compounded Half Yearly = R/2

i) Time Period = 3/2 x 2 = 3 Years
   Rate = 8/2 = 4%

ii) Time Period = 2 x 2 = 4 Years
    Rate = 4/2 = 2%