Answer:
Based on the information provided, the correct choice is:
fail to reject it
Here are the key points:
• The mean depression score for the sample of 20 4th graders was 4.4.
• The counselor tested the null hypothesis that these 4th graders were less depressed than the general 4th grader population.
• The t score calculated was 2.8.
To reject the null hypothesis and conclude the sample differs from the population, we would need a high enough t score. But the t score of 2.8 is not conclusively high enough here.
Some additional considerations:
• The general 4th grader population mean is 5, so the sample mean of 4.4 is a bit lower, but not drastically. This suggests the sample may not differ hugely from the population.
• There is no information on the variation or standard deviation for either the sample or population. Without this, we can't determine if a t score of 2.8 actually signifies a statistically significant difference.
• The sample size of 20 is decent but not very large. Larger sample sizes provide more conclusive results.
• No p-value is given, making it hard to judge if the t score of 2.8 is high enough to reject the null hypothesis. By convention, p<0.05 is often used but we don't have the p-value here.
So overall, there is not enough definitive evidence provided to conclusively reject the null hypothesis. The t score of 2.8 alone is probably not high enough, given the considerations around sample size, variation, and lack of a p-value. More data and analysis would be needed to make a firm decision either way.
Therefore, the correct choice is: "fail to reject it". There is not enough information given in this question and results to conclusively reject the null hypothesis.
Explanation: