A bag contains 2 n+1 coins. It is known that n of these coins have a head on both sides, whereas the remaining n+1 coins are fair. A coin is picked up at random from the bag and tossed. If the probability that the toss results in a head is 31 42 , then n is equal to

Step-by-step solution

The probability that the toss results is a tail = (n+1) 2(2 n+1) 1- (n+1) 2(2 n+1) is the probability that the toss result is a head. array lc & 1- n+1 2(2 n+1) = 31 42 & 4 n+2-n-1 4 n+2 = 31 42 & 3 n+1 4 n+2 = 31 42 & 126 n+42=124 n+62 & 2 n=20 & n=10 array