Question

The given graph shows the cost of maintaining the lighthouse, $y$ (in $), per the number of lighthouses, $x$.

Interpret the graph and choose the correct conclusions from the graph.

• A. The equation of the graph is $y=\frac{300}{x}$.
• B. Both B and C
• C. The cost of maintaining four lighthouses is $\$1200$.
• D. The equation of the graph is $y=300x$.

Answer 1

The correct option is B Both B and C

$\begin{array}{ccc}\text{Number of lighthouse, x}& 2& 3\\ \text{Cost of maintenance (in}\$),y& 600& 900\\ & (600=300\times 2)& (900=300\times 3)\end{array}$
The graph shows the relationship between the cost of maintaining the lighthouse (in $\$),y$, and the number of lighthouses, x. Each value of the cost of maintaining the lighthouse, y, is obtained by multiplying 300 to the number of lighthouses, x.
Hence, the equation for the relation shown in the graph is $y=300\times x$ or y = 300x.
Option B is correct.
The cost of maintaining four lighthouses will be obtained by putting x = 4 in the equation y = 300x.
Hence, the cost of maintaining four lighthouses $=300\times 4=\$1200$
Option C is also correct. Hence, option D is correct.