Answer:
There is evidence at 95% level to support the claim that he average sodium content for a single serving of such a cereal is greater than 220 milligrams
Explanation:
Create hypothesis as

(Right tailed test at 5% significance level)
Mean difference =

STd error =

df =19
Test statistic t = mean diff/std error = 4.399
p value =0.0000155
Since p value is <0.05 reject null hypothesis.
There is evidence at 95% level to support the claim that he average sodium content for a single serving of such a cereal is greater than 220 milligrams