Aggressive "weed out" policies?

[austinmshauri]

Two examples at one top 20 college(Tufts) are an older cousin(graduated in the early '80s) and a post-college roommate(graduated in the mid-'90s) ~ 10 years apart who found around 60% of their respective intro chem/bio class were “weeded out” with D or F grades* which meant they couldn’t continue in the major unless they took that very same course over again and passed it with a C or higher.

How do you find out how many students pass a particular class?