Answer:
strong enough, at the 5 percent level of significance, to establish the claim of the toothpaste advertisement
Step-by-step explanation:
Let X be the Cavities per year for their age group
X is N(3,1)
Population mean and std deviation are given here
Sample size n = 2500
Sample mean = 2.95
Let us create hypotheses as

(left tailed test)
Mean difference = 
Std error of mean = 
Z= mean difference/std error = -2.5
Level of significance =5%
For one tailed test at 5% significance level Z critical = -1.645
Since -2.5 <-1.645 we reject null hypothesis
These data are strong enough, at the 5 percent level of significance, to establish the claim of the toothpaste advertisement