In an examination taken by 500 candidates, the average and S.D of marks obtained are 40% and 10% respectively. Assuming normal distribution, find (i) how many have scored above 60%,(ii) how many will pass if 50% is fixed as the minimum marks for passing, (iii) how many will pass if 40% is fixed as the minimum marks for passing, and (iv) what should be the minimum percentage of marks for passing so that 350 candidates pass.