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Psychologists had a hypothesis that watching TV food commercials causes children to eat more snacks.
They randomized 500 children between a treatment group and a control group. Each child was asked to watch a cartoon with a commercial break in a private room containing a large bowl of goldfish crackers. The treatment group watched food commercials (mostly snacks), while the control group watched non-food commercials (games and entertainment products). Once the child finished watching, the experimenters measured how many grams of crackers the child ate.
The results of the experiment showed that the mean amount of crackers eaten by the treatment group is 8 grams greater than the mean amount of crackers eaten by the control group. To test whether the results could be explained by random chance, the researchers created the table below, which summarizes the results of 1000 re-randomizations of the data (with differences between means rounded to the nearest 2 grams).
According to the simulations, what is the probability of the treatment group's mean being higher than the control group's mean by 8 grams or more?
  • Your answer should be
  • an integer, like 6
  • an exact decimal, like 0, point, 75
  • a simplified proper fraction, like 3, slash, 5
  • a simplified improper fraction, like 7, slash, 4
  • a mixed number, like 1, space, 3, slash, 4
  • a percent, like 12, point, 34, percent
Assume that if the probability you found is lower than 5, percent, then the result should be considered significant.
What should we conclude regarding the experiment's result?
Please choose from one of the following options.
Treatment group mean minus Control group meanFrequency
minus, 103
minus, 820
minus, 657
minus, 4122
minus, 2187