A's weight varies inversely as C's weight squared. When A weighs 20 kilograms, C weighs 10 kilograms. How much does A weigh when C weighs 5 kilograms?

Question

A's weight varies inversely as C's weight squared.  When A weighs 20 kilograms, C weighs 10 kilograms.  How much does A weigh when C weighs 5 kilograms? 

Answer 1

Since A varies inversely with C² then our initial equation is A = k/C²

Where k is a constant which we need to find

 

We have initial info of when A = 20 kg, C = 10 kg.  From this we can find k

 

20 = k/10²

20 = k/100

k = 2000

 

Now use this information to plug in with the new value of C and the value of k

 

A = 2000/5² = 2000/25 = 80 kg

 

A weighs 80 kg when C weighs 5 kg