commercial math help..plz

**given that carbon decays at a constant rate in a such a way that it reduces to 20% in 1562 years. the age of the wooden piece in which the carbon is only 4% of the original**

given that carbon-14 decays at a constant rate in such a way that it reduced to 25% in 1244 years.. find the age of the tree in which the carbon is only 6.25% of the original

the simple interest and compound interest on a certain sum for 2 years are rs. 800 and rs. 880 respectively. the rate of interest (in % p.a.) on both the sums is the same. if the interest on the sum lent at compound interest is compounded annually, find the rate of interest (in % p.a.)

A man wants to divide rs.145000 between his son and daughter who are 12 years and 14 years respectively, in such a way that the sum invested at the rate of 25/3% per annum compounded annually will give the same amount to each, when they attain 16 years. how should he divide the sum

A man invested one-fifth of the capital at 5% p.a., one - sixth of the capital at 6% p.a., and the rest at 10% p.a., simple interest. If the annual interest received on his investment is rs.150, then find the capital.

**How much % greater than the cost price should a shopkeeper mark his goods so that after allowing a discount of 22% on the marked price, he gains 17%.**

thanks a lot.(Bow)(Bow)

Re: commercial math help..plz

Hint: 4% is one fifth of 20%...

Re: commercial math help..plz

More importantly, (.2)(.2)= .04.

Kohila, what kind of help do you want? You have listed a series of problems without any indication of what you **do** understand or what you **can** do on these. I don't see how anyone can give hints that will help you if we don't know that.

(I am assuming that you **don't** want us just to do the problems for you because that way you won't learn anything- and surely you will have to do problems like this on tests.