Pulse Asia thinks that customer monthly cell phone bill has decreased and now average under $800$ pesos per month. A researcher wishes to test this claim. Suppose asample is taken with the following results: n$=90,$ sample average or x bar $=850$pesos $($Assume o $=10$ is known$).$ Using $6$ steps, test the hypothesis at $0\mathrm{.}05$ level ofsignificance.