The power company in a large city wanted to determine if households spend more, on average, on electricity in the summer months than in the winter months. An SRS of 125 homes was selected, and the bills for their summer months and winter months were compared. The mean difference in the bills (summer – winter costs) was $9.13 with a standard deviation of $8.26. Do the data provide convincing evidence that households spend more, on average, during summer than during winter on electricity? Give the values indicated. What is the value of ndiff?