normal distribution and z scores

hi shorty. i can solve the equations on paper(the simpler stuff still) . i should have been more clear. its just 15 yrs since i did statistics so it was more if the method i was using was correct; given the info available(finding unknown mean and sd etc). and if (assuming finishing position is normal distributed) i can go on to use the estimates for mean and sd to get probabilities for other finishing positions accurately. ie 1st-15th or 1st-40th. i have solved the eq on the spreadsheet now. seems like there could be an easier way tho or a method i may need for harder eq. currently im doing it in bits over numerous cells. will check your links a bit later if thats what they explain. (answered here before checking them. brains bit tired for maths now)