Required probability =2019×21+201×12019×21=2119∴n m=2119⇒n2−m2=441−361=80
A bag contains 19 unbiased coins and one coin with head on both sides. One coin drawn at random is tossed and head turns up. If the probability that the drawn coin was unbiased, is nm,gcd(m,n)=1, then n2−m2 is equal to :
Held on 7 Apr 2025 · Verified 6 Jul 2026.
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