JEE Main 2026 · 6 Apr · Shift 1 · Mathematics Q10

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MathematicsSingle correct+4 / -1Question 10 of 75

A bag contains $(N+1)$ coins − N fair coins, and one coin with 'Head' on both sides. A coin is selected at random and tossed. If the probability of getting 'Head' is $\dfrac9{16}$ , then N is equal to:

Answer and worked solution

Official answer: B

Total probability.
$P(H)=\frac{N\cdot\frac12+1}{N+1}=\frac{N+2}{2(N+1)}=\frac9{16}.$

Solve. $16N+32=18N+18$ , so $N=7$ .

(B)

Topics:Conditional probability

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JEE Main 2026 · 6 Apr · Shift 1, Mathematics question 10