I made this recipe from Paula of the blog Bell'Alimento. It's so yummy you should try it : http://www.bellalimento.com/2009/11/10/bolognese-sauce/ I don't really know the number of serving. But I got 2 jars of this sauce.
In a LARGE deep sided pan (chicken fryer size) add your olive oil and heat over medium heat. When pan is hot, add the carrots, celery, onion & garlic and saute over low heat for 20-25 until completely soft & tender. Stir as necessary.
Add your meats, season with salt and pepper and cook until completely brown. When meat is browned, add the tomato paste and allow to brown, approx 5 minutes. When brown add your wine & allow to reduce by half. Season with salt.
When wine has reduced add in enough water to cover the sauce by 1″. Let sauce simmer on LOW. Stirring occasionally and when liquid levels are low add more water. Cooking & reducing all while simmering. Sauce needs to cook for a MINIMUM of one hour but is best after 2-3 or even more hours.
Prepare your spaghetti according to package directions. When pasta is al dente, reserve a bit of pasta water & remove pasta from pot, drain & transfer into sauce pan. Mix together with tongs so sauce & pasta incorporate. Add a nice handful or two of Parmigiano Reggiano & serve immediately.