Help me I don’t understand what to do

Which of the following is another way to express the difference between -5 and 8?

Jocelyn estimates that a piece of wood measures 5.5 cm. if it actually measures 5.62 cm, what is the percent error of jocelyn’s estimate? a. 2.13% b. 2.18% c. 12% d. 46.83%

Astudy claims that the mean age of online dating service users is 40 years. some researchers think this is not accurate and want to show that the mean age is not 40 years. identify the null hypothesis, h0, and the alternative hypothesis, ha, in terms of the parameter μ. select the correct answer below: h0: μ≥40; ha: μ< 40 h0: μ≤40; ha: μ> 40 h0: μ≠40; ha: μ=40 h0: μ=40; ha: μ≠40