A farmer believes that the new variety of tomatoes he used this year has yielded more tomatoes per plant than what he used to obtain, which was 5 tomatoes per plant. To check that he uses a random sample of 10 tomato plants that produced on average 5.55 tomatoes with a standard deviation of 1.23.

a) Is there convincing evidence that the new variety gives a higher yield at a 5% significance level?

b) Give a P-value to answer this question.