JEE Main 2026 · 5 Apr · Shift 1 · Mathematics Q7

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MathematicsSingle correct+4 / -1Question 7 of 75

A letter is known to have arrived by post either from KANPUR or from ANANTPUR. On the envelope just two consecutive letters AN are visible. The probability, that the letter came from ANANTPUR, is:

\dfrac7{10}

\dfrac{10}{17}

\dfrac{12}{19}

\dfrac7{19}

Answer and worked solution

Official answer: B

Pairs of consecutive letters.

KANPUR: KA, AN, NP, PU, UR. $P(\text{AN}\mid K)=\tfrac15$ .
ANANTPUR: AN, NA, AN, NT, TP, PU, UR. $P(\text{AN}\mid A)=\tfrac27$ .

Bayes (equal priors):
$P=\frac{2/7}{2/7+1/5}=\frac{10}{17}.$

(B)

Topics:Bayes' theorem

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JEE Main 2026 · 5 Apr · Shift 1, Mathematics question 7