$2)$ a$.)$ Explain what a S$-$Curve is$.$ b$.)$ A project commenced in January and is planned to be completed in $10$ months at a cost of $1000$ per month. After $6$ months the planned value $($PV$)$ is estimated to be $6000,$ theproject is $68\%$ completed, and the actual expenditure, actual cost $($AC$),$ is $5500.$Determine the status of the project after $6$ months. c$.)$ You are the project manager on a project. The project is expected to be completed in $10$months at a planned cost of $1000$ per month. After $6$ months the project is $55\%$ completed. The planned value after $6$ months is $6000,$ and the actual certifiedexpenditure after $6$ months is $6750.$ Determine the status of the project after $6$ months.d$.)$ Explain your results, i$.$e$.,$ the S$-$curve produced in both question $2$b and question $2$c$.$