Please explain step by step!

A marketing manager for a cell phone company claims that the percentage of children aged 8- 12 who have cell phones differs from 55%. In a survey of 880 children aged 8-12 by a national consumers group, 450 of them had cell phones.

a. Can you conclude that the manager's claim is true? State your hypotheses and conclusion and interpret the results. Use an = 0.01 level of significance and the P-value method using your table of statistical values.

b. Construct a 98% confidence interval for the proportion of the children aged 8-12 who have a cellphone and interpret it.