find the effective rate percent per annum.

Question

which is equivalent to a nominal rate of 10% per annum interest payable half - yearly?

Answer 1

By interest paid half yearly I gather you mean semi-annually, or twice per year

 

For effective interest rate calculation from a nominal rate use the formula

(1+i/n)ⁿ-1 where i is the nominal interest rate and n is the number of times compounded annually

 

Effective rate = (1+.1/2)²-1 = .1025 or 10.25%