Answer:
18/245.
Explanation:
Total number of coins = 12+15+23 = 50.
Prob(Karen chooses a dime) = 15/50 = 3/10.
Prob(Mikah then chooses a quarter) = 12/49. ( Karen has already removed one coin)
Prob(of Karen choosing a dime then Mikah a quarter)
= 3/10 * 12/49
= 36/490
= 18/245.