Hello,
No you will not have any problems during your placements at IIT Bombay. You just need to clear the minimum eligibility requirements of B.Tech marks. Which is generally 65-70% in top companies like google. Just maintain good marks in M.Tech, you b.tech marks won't affect your placement. And in IIT placements ability is tested more than marks.
Candidates can check B.Tech Cut off for Top IITs & NITs here.
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