Solve for $r$ in the proportion.
$\frac{10}{3}=\frac{r}{3.9}$
Answer (1)
We have the proportion 3 10 = 3.9 r .
Multiply both sides by 3.9 to isolate r : r = 3 10 × 3.9 .
Simplify the expression: r = 3 39 .
The solution is: 13 .
Explanation
Understanding the Problem We are given the proportion 3 10 = 3.9 r and we need to solve for r .
Isolating r To isolate r , we multiply both sides of the equation by 3.9: r = 3 10 × 3.9
Simplifying the Expression Now we simplify the expression: r = 3 10 × 3.9 = 3 39 = 13
Final Answer Therefore, the value of r is 13.
Examples
Proportions are useful in everyday life. For example, if you know that 3 apples cost 2 , yo u c an u se a p ro p or t i o n t o f in d t h ecos t o f 15 a ppl es . S e tt in gu pt h e p ro p or t i o n \frac{3}{2} = \frac{15}{x} , yo u c an so l v e f or x$ to find the cost of 15 apples. This concept is widely used in cooking, scaling recipes, and calculating costs.
