Question

Kevin has an equal number of dimes, nickels, and quarters in his piggy bank. He randomly picks a coin, replaces it, and picks another coin. What is the probability that the sum of the two coins picked is at least 30 cents?

Answer 1

Answer:

$\dfrac{5}{9}$

Step-by-step explanation:

Let's get the sample space first. What are the possibilities? Kevin could pick

2 nickels = 10 cents,

2 dimes = 20 cents,

2 quarters = 50 cents,

1 nickel + 1 dime = 15 cents,

1 nickel + 1 quarter = 30 cents,

1 quarter + 1 dime = 35 cents.

There are two ways of picking in each of the last three---by reversing the order of picking e.g. nickel then dime, and dime them nickel. In all, we have 9 possible outcomes.

Of these, 5 yield a sum that is at least 30:

quarter + quarter (50c), nickel + quarter (30c, twice) and quarter + dime (35c, twice)

The probability of having the sum of two coins equal to, at least, 30 is thus $\dfrac{5}{9}$.

Answer 2

Answer:

5/9 <3

I Got It Right On The Test