1. ## 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.

2. ## Re: commercial math help..plz

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

3. ## 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.