Checkpoint: Two-Way Tables Solutions

The moon is in the sky for 300 nights each calendar year in Pennsylvania. Of the 195 clear nights recorded, there was no moon on 35 nights.

  1. Create a two-way table.
  Moon (M) No Moon (M’) Total
Clear (C) 300140=19535=                                    160 35 195
Not Clear (C’) 17030=               140 6535=             30 365195=                 170
Total 300 365300=                 65 365
  1. Determine the probability that the night is overcast and there is no moon.

PC  M=30365=0.082

  1. P(clear or moon)

=195365+300365160365=335365=6773=0.918

Note

“Overcast” translates to “not clear.”

 

Q: Is this a two-way table or a joint frequency table? Explain.

A: This is a two-way table because each cell has a total, not a percentage.

 

Only the final answer is needed in each cell. The work shown is included as a guide.

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