A genetics class decides to recreate the garden pea breeding

A genetics class decides to re-create the garden pea breeding experiments of Gregor Mendel. They grow several garden pea plants from random crosses of purple-flowered plants and test whether the resulting purple flower:white flower ratio is consistent with the expected 3:1 ratio, based on independent assortment of alleles. A concern is that the initial parental plants might have had a low level of heterozygosity, meaning the frequency of purple-flowered offspring could be higher than expected.

With a sample of 120 plants, what percentage of purple flowered plants would be needed to produce a Chi-squared value of 4 or higher for a Goodness of Fit test; thus confirming their fear?

(Make sure to answer as a percentage, not a fraction. Round your percentage to the nearest 1%. Keep in mind that it might not be possible to get an exact Chi-squared value of 4 for 1% incremental changes.)

Solution

This is the test with minimum of purple flowered plants would be needed to produce a Chi-squared value of 4 or higher.

Goodness of Fit Test

observed

expected

O - E

(O - E)