A dihybrid cross is expected to give a 9:3:3:1 ratio. Out of 160 offspring, observed counts are 99, 28, 25, 8. The chi-square statistic for goodness of fit (df = 3) is approximately
- A
(borderline at p = 0.05)
- B
(data perfectly fits)
- C
(reject 9:3:3:1)
- Dcheck_circle
(fails to reject 9:3:3:1)
Explanation
Expected: 90, 30, 30, 10. χ² = Σ(O-E)²/E = 81/90 + 4/30 + 25/30
<ul> <li>4/10 ≈ 0.9 + 0.13 + 0.83 + 0.4 ≈ 2.27. Closer to ~1.4 than to large values; well below the 7.815 critical value at α=0.05, df=3 — fail to reject.</li> </ul>