Example Determining Spot Speed Sample Size

As part of a class project, a group of students collected a total of $120$ spot speed samples at a location and determined from this data that the standard variation of the speeds was $+-6m\frac{i}{h}.$ If the project required that the confidence level be $95\%$ and the limit of acceptable error was $+-1\mathrm{.}5m\frac{i}{h},$ determine whether these students satisfied the project requirement.