Question

A varies jointly with b and c. a=10 b=5 and c=15. find c when a=15 and b=10

Answer 1

Let's begin by identifying key information given to us:

`\begin{gathered} a\alpha bc\Rightarrow a=kbc \\ a=kbc \\ a=10,b=5,c=15 \\ \text{Substitute these into the equation, we have:} \\ 10=k\cdot5\cdot15 \\ 10=75k\Rightarrow75k=10 \\ 75k=10 \\ k=(10)/(75)=(2)/(15) \\ k=(2)/(15) \\ \\ When;a=15,b=10 \\ a=kbc \\ 15=(2)/(15)\cdot10\cdot c \\ 15=(2\cdot10)/(15)c \\ 15=(20)/(15)c \\ 15\cdot15=20c\Rightarrow225=20c \\ 20c=225 \\ c=(225)/(20)=11.25 \\ c=11.25 \end{gathered}`