Susan has a bag with 5 mint sticks, 3 jelly treats, and 12 fruit tart chews. If she eats one piece every 8 minutes, what is the probability her first two pieces will be a fruit tart chew and a jelly treat and represent as a percent to the nearest tenth if necessary?

A.
63.2%
B.
0%
C.
9%
D.
9.5%

1 answer

To determine the probability that Susan's first two pieces of candy will be a fruit tart chew followed by a jelly treat, we first need to find out the total number of candy pieces in the bag and then the probabilities of each event occurring in sequence.

  1. Total pieces of candy:

    • Mint sticks: 5
    • Jelly treats: 3
    • Fruit tart chews: 12

    Total number of pieces = 5 + 3 + 12 = 20 pieces.

  2. Probability of the first piece being a fruit tart chew:

    • There are 12 fruit tart chews out of 20 total pieces. \[ P(\text{first = fruit tart}) = \frac{12}{20} = 0.6 \]
  3. Probability of the second piece being a jelly treat given that the first was a fruit tart chew:

    • After eating one fruit tart chew, there will be 19 pieces left (20 - 1) with 3 of them being jelly treats. \[ P(\text{second = jelly treat | first = fruit tart}) = \frac{3}{19} \]
  4. Combined probability of both events: \[ P(\text{fruit tart first and jelly treat second}) = P(\text{first = fruit tart}) \times P(\text{second = jelly treat | first = fruit tart}) = \frac{12}{20} \times \frac{3}{19} \]

    Calculating this: \[ P = \frac{12}{20} \times \frac{3}{19} = 0.6 \times \frac{3}{19} = \frac{1.8}{19} \]

    Now we convert \( \frac{1.8}{19} \) to a decimal: \[ \frac{1.8}{19} \approx 0.0947368421 \]

    To express this as a percentage: \[ 0.0947368421 \times 100 \approx 9.47368421% \]

    Rounding to the nearest tenth: \[ \approx 9.5% \]

Thus, the probability that Susan's first two pieces will be a fruit tart chew followed by a jelly treat is 9.5%.

The correct answer is D. 9.5%.