A bag contains 2n + 1 coins, n coins have tails on both sides, whereas n + 1 coins are fair. A coin is picked on random from the bag and tossed. If the probability that toss in tail is 31/42, total numbers of coins in the bag are
1
20
2
21
3
22
4
23
A bag contains 2n + 1 coins, n coins have tails on both sides, whereas n + 1 coins are fair. A coin is picked on random from the bag and tossed. If the probability that toss in tail is 31/42, total numbers of coins in the bag are