LabBench Activity

How to Calculate the Expected Value

In a cross between two heterozygous individuals, the offspring would be expected to show a 3 : 1 ratio. For example, in Case 1, three-fourths of the individuals would have red (wild-type) eyes, and one-fourth would have sepia eyes.

If there are 44 offspring, how many are expected to have red eyes?

We expect three-fourths to have red eyes.
3 / 4 of 44 = 33

If there are 44 offspring, how many are expected to have sepia eyes?
1 / 4 of 44 = 11

Now you are ready to calculate chi-square.