When Moshe comes down from Har Sinai & sees the golden calf he says ‘Whoever is for God, join me.’ After the Leviim gather he orders them to grab their swords & execute anyone involved. They do so & the Torah tells us that ‘approximately 3,000 men died that day’ (Exodus 32:26-28). We know that there were around 600,000 men at Har Sinai so the question is did only 3000 ppl participate in this affair (just half a percent of the population) or were the 3000 the instigators/leaders & many more followed them?
I'm sure there are many more, but wanted to share 4 approaches as to how many people sinned/ participated in the golden calf.
1) Majority of the nation literally sinned (via their innermost thoughts)
The Ramban on Shemos 32:7 writes that even though the people killed as a result of the golden calf were comparatively few (ie 3,000), the majority of the nation had sinned.
אמר השם למשה כי עשו שתים רעות ... והנה העבירה הראשונה לא ידענה רק השם לבדו שהוא יודע תעלומות לב, והשנית מעשה הזובחים החוטאים שבהם כאשר פירשתיוהנה רוב העם חטאו במעשה העגל, כי כן כתוב ויתפרקו כל העם את נזמי הזהב, ולולי זה לא היה הכעס בכולם לכלותם. והנה הנהרגים והנגפים מועטים, כי ברובם היה החטא במחשבה רעה, כמו שפירשתי
Hashem said to Moshe '[Bnei Yisrael] did two bad things' ... in terms of the first aveirah that Bnei Yisrael did, only Hashem who knows a person's innermost thoughts knows what they did, the second aveirah was building, sacrificing to and worshiping the golden calf as I've previously explained. And the majority of of the nation sinned with the golden calf, as the passuk says: "And all the people took off the gold rings that were in their ears." If not for this, Hashem would not have been as angered at them to destroy them. Those who were killed and struck in the plague were few, but the majority nonetheless sinned with bad thoughts, as I have explained
2) Only 3,000 people fully & "halachically" sinned
(as understood and explicitly stated by this OU.org article)
The Malbim on Shemos 32:35 (although not fully stated outright) seems to maintains that the total number people killed was 3,000 (by the plague)
ויגוף, אמנם הע"ר שהם עשו את העגל נגפו במגפה, ופי' חז"ל שהם אלה שלא היו שם עדים והתראה, כי מן בני ישראל שעבדו היו עדים אלה שלא עבדו, אבל הע"ר שכולם עבדו לא היו עדים כי הם בכללם היו העושים, וע"כ הע"ר כולם נגפו במגפה כי להם לא נשבע ה' להביאם לארץ ומשה לא התפלל עליהם כנ"ל (פסוק י"א), ובאר שלא אהרן עשה רק הם עשו, כי אהרן היה אנוס כנ"ל:
(translation adapted from said OU.org article)
" although only a small portion of Bnai Yisrael participated in the sin of the Egel, a large portion of the Erev Rav were involved in the sin. Therefore, among Bnai Yisrael there were many innocent people that forewarned their neighbors to not worship the Egel. If their forewarning was disregarded these same individuals were available to serve as witnesses of the sin.
... among the Erev Rav there were few if any innocents who forewarned their neighbors. And there were few members of the Erev Rav who were untainted by the sin of the Egel and qualified to testify against others... these members of the Erev Rav were killed by the plague
3) Only a few literally sinned, most of the nation "passively" sinned
The Sforno on Shemos 32:27 writes (fleshed out by the aforementioned OU.org article):
although only a small portion of the nation actually worshipped the Egel, many others stood by passively and did little to prevent their neighbors from violating the prohibition against idolatry – one of the most important injunctions of the Torah. They could have acted responsibly and forcibly prevented the sin from taking place. But they could not bring themselves to take aggressive action. As a result, the sin of the Egel took place. In other words, the sin was the result of the actions of the few and the passivity of the majority.
Hashem wanted to punish both those who sinned actively by worshipping the Egel and those who sinned through their passivity – by not taking the action necessary to prevent the sin. The sinners were punished by death. Those who failed to act were punished by being forced to watch the executions.
4) The number of people who sinned is purposefully not mentioned
The Tilas Aitz"al (ie me/ my "Chavos Yair"-inspired name) is of the opinion that this number is purposefully opaque so as not to embarrass Bnei Yisrael. Since the Erev Rav instigated this whole episode, they weren't really part of Bnei Yisrael and were wiped out- the Torah doesn't mind telling us how many people these were. But the children of Avraham, Yitzchak, & Yaakov? As bad as our actions were, the Torah HaKedoshah still doesn't want to embarass us and refrains from explicitly stating the number.