A researcher thinks that a person's mood has an effect on how helpful that person is likely to be. To test this, the researcher has some research participants come to the laboratory where they are first given a difficult test and then either heavily praised or strongly criticized for their test performance. Afterwards, participants are asked to help the researcher's assistant move some heavy boxes into another room. The researcher makes careful note of how many and which participants help with moving the boxes. In this example, the hypothesis is

a person's mood has an effect on how helpful that person is likely to be

Explanation:

The hypothesis is the researchers opinion before the start of the experiment. The researchers opinion is that "a person's mood has an effect on how helpful that person is likely to be" this is the hypothesis before the start of the study. The null hypothesis in this study is most likely; a persons mood has no effect on how helpful that person is likely to be , i.e. effect of mood on the likelihood of an individual to help is zero while the alternative is that the effect of mood on the likelihood of an individual to help is not zero.

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