Answer:
1/3
Step-by-step explanation:
The only ways to get at least 30 cents from two coins are:
- 1 nickel (5 cents) + 1 quarter (25 cents) - case 1
- 1 dime (10 cents) + 1 quarter (25 cents) - case 2
- 1 quarter (25 cents) + 1 quarter (25 cents) - case 3
Case 1:
The probability of choosing a nickel is 1/3 and the probability of choosing a quarter next is also 1/3. Multiply these together:
(1/3) * (1/3) = 1/9
Case 2:
The probability of choosing a dime is 1/3 and the probability of choosing a quarter next is also 1/3. Multiply these together:
(1/3) * (1/3) = 1/9
Case 3:
The probability of choosing a quarter is 1/3 and the probability of choosing another quarter next is also 1/3. Multiply these together:
(1/3) * (1/3) = 1/9
Finally, add up these probabilities:
1/9 + 1/9 + 1/9 = 3/9 = 1/3
