Step 1: Find the rate per minute
The machine makes 135 thermometers in 18 minutes. To find the rate per minute, we divide the total thermometers by the total minutes:

$$
\(\text { Rate }=\frac{135 \text { thermometers }}{18 \text { minutes }}=7.5 \text { thermometers per minute }\)
$$


Step 2: Calculate the production for one hour
Since there are 60 minutes in one hour, we multiply the rate per minute by 60 :

$$
\(\text { Total in one hour }=7.5 \times 60=\mathbf{4 5 0}\)
$$


Alternative Method: Using Ratios
You can also set up a proportion:

$$
\(\begin{gathered}
\frac{135}{18}=\frac{x}{60} \\
18 x=135 \times 60 \\
18 x=8100 \\
x=\frac{8100}{18}=\mathbf{4 5 0}
\end{gathered}\)
$$