Project W may yield a return of 2m with a probability of 0.3, or a return of

Question:

Project W may yield a return of £2m with a probability of 0.3, or a return of £4m with a probability of 0.7. Project X may earn a negative return of £2m with a probability of 0.3 or a positive return of £8m with a probability of 0.7. Project Y yields a return of £2m which is certain. Compare the mean return and risk of the projects.