JEE Main 2020 (2 Sep, Shift 1) Maths Q68: Bayes' Theorem

Question

Box I contains 30 cards numbered 1 to 30 and Box II contains 20 cards numbered 31 to 50. A box is selected at random and a card is drawn from it. The number on the card is found to be a non-prime number. The probability that the card was drawn from Box I is :

(1) $\frac{8}{17}$ Official answer
(2) $\frac{4}{17}$
(3) $\frac{2}{5}$
(4) $\frac{2}{3}$

Official answer

Option 1

NTA final key (Sep 2020).

Accepted Answer

Option 1: $\frac{8}{17}$

Answer

$\frac{8}{17}$

Answer

$\frac{4}{17}$

Answer

$\frac{2}{5}$

Answer

$\frac{2}{3}$

JEE Main 2 September 2020, Shift 1, Maths Q68

Same idea in other shifts