CHI SQUARE M&M LAB ANALYSIS QUESTIONS



Name ______________________________________________________

CHI SQUARE LAB WS …

Can You Beat the Odds?! (

Data:

❖ Probability of Rolling a 7 = _________________________________________________________________________________

|Name |Total # of Rolls |Expected # of 7s |Observed # of 7s |

| |20 | | |

| |20 | | |

| |20 | | |

| |20 | | |

Analysis – Show your work!

1. Perform a Chi Square Analysis to determine if your observed results differ significantly from the expected results.

• Record the null hypothesis.

• Calculate Chi Square.

• Determine the degrees of freedom.

• Use the Probability Table below to determine the P value.

• Record the P value and explain if the null hypothesis is accepted or rejected.

Accept the null hypothesis Reject

|Degrees of |Probability |

|Freedom | |

| |0.90 |0.50 |0.25 |0.10 |0.05 |0.01 |

|1 |0.016 |0.46 |1.32 |2.71 |3.84 |6.64 |

|2 |.0.21 |1.39 |2.77 |4.61 |5.99 |9.21 |

|3 |0.58 |2.37 |4.11 |6.25 |7.82 |11.35 |

|4 |1.06 |3.36 |5.39 |7.78 |9.49 |13.28 |

|5 |1.61 |4.35 |6.63 |9.24 |11.07 |15.09 |

2. In pea plants, tall is dominant & short is recessive. The genotypic ratio of a cross between F1 pea plants shows the following results:

• 34 homozygous dominant plants

• 35 heterozygous plants

• 31 homozygous recessive plants

Calculate the chance that the deviation from the expected values in this cross is due to random chance alone.

3. When a normal-winged fruit fly was crossed with a vestigial-winged fruit fly, 154 normal-winged flies and 139 vestigial-winged flies were produced.

a. What is the probable genotype of your normal-winged fly?

b. Does the data fit your hypothesis? (Use a Chi-Square test to determine this)

4. In corn, purple color (P) is dominant and yellow (p) is recessive; smooth kernels (S) are dominant and shrunken kernels (s) are recessive. An ear of corn has the following totals:

• 216 purple, smooth kernels

• 79 purple, shrunken kernels

• 65 yellow, smooth kernels

• 21 yellow, shrunken kernels

a. What is the original cross?

b. State the null hypothesis.

c. Calculate Chi Square.

d. How many degrees of freedom are there?

e. What is the probability value for the data?

f. Is the null hypothesis accepted or rejected? Explain.

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