A monohybrid cross produces 200 offspring: 160 with the dominant phenotype and 40 with the recessive. A 3:1 ratio is expected. What is the chi-squared value and conclusion at p = 0.05 (critical value 3.84 for 1 degree of freedom)?
Answer and explanation
Correct answer: A. Chi-squared = 2.67; the difference is not significant
- Step 1: Expected values: 150 and 50. Step 2. . Step 3. 2.67 is less than 3.84, so the null hypothesis is retained: any difference is due to chance. Answer: Chi-squared = 2.67; the difference is not significant. Why not the others: a value below the critical value is not significant; 2.67 is below 3.84, so it is not significant; 5.33 does not follow from the observed and expected numbers.
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