Three of the ten lots are answered by A, and each person draws one and does not put it back. A is the fifth draw. What are the chances that A will answer?

Probability of the second lottery: 3/10 * 2/9+7/10 * 3/9 = 3/10.

Probability of the third lottery: 3/10 * 3/10 *1/8+3/10 * 7/10 * 2/8 * 7/10.

....

...？ 3/ 10

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