Data was collected for 300 fish from the North Atlantic. The length of the fish (in mm) is summarized in the GFDT below.

Question

Lengths (mm) Frequency
120 - 139 1
140 - 159 16
160 - 179 71
180 - 199 108
200 - 219 83
220 - 239 18
240 - 259 3

What is the class midpoint for the seventh class?

Answer 1

To calculate the class midpoint for any given class, you can use the formula:

\[ \text{Class midpoint} = \frac{\text{Lower limit} + \text{Upper limit}}{2} \]

For the seventh class, which is:

• Lengths: 240 - 259 mm

The lower limit is 240 mm and the upper limit is 259 mm.

Now applying the formula:

\[ \text{Class midpoint} = \frac{240 + 259}{2} = \frac{499}{2} = 249.5 \text{ mm} \]

So, the class midpoint for the seventh class is 249.5 mm.