Answer:
9/22
Step-by-step explanation:
They are 30 25-fils coins, 25 10-fils coins, 40 5-fils coins and 15 1-fils coins.
The total number of fils coins = 30 + 25 + 40 + 15 = 110 coins
The probability of picking n-fils coin = number of n fils coin / total number of fils coins.
Therefore:
The probability of picking 25-fils coin = number of 25 fils coin / total number of fils coins = 30/110 = 3/11
The probability of picking 10-fils coin = number of 10 fils coin / total number of fils coins = 25/110 = 5/22
The probability of picking 5-fils coin = number of 5 fils coin / total number of fils coins = 40/110 = 4/11
The probability of picking 1-fils coin = number of 1 fils coin / total number of fils coins = 15/110 = 3/22
The probability that the first coin he picks is a 25-fils coin or a 1-fils coin = The probability of picking 25-fils coin + The probability of picking 1-fils coin = 3/11 + 3/22 = 9/22
