A glass jar contains 1 red, 3 green, 2 blue and 4 yellow marbles. If a single marble is chosen at random from the jar, what is the probability that it is yellow or green?

Answer

To solve the problem, we need to find the probability of selecting a yellow or green marble from the jar. Let's break it down step by step.

### Step 1: Count the total number of marbles in the jar.
- Red marbles: 1
- Green marbles: 3
- Blue marbles: 2
- Yellow marbles: 4

**Total number of marbles = Red + Green + Blue + Yellow**
Total = 1 + 3 + 2 + 4 = 10

### Step 2: Count the number of favorable outcomes (yellow or green marbles).
- Number of green marbles = 3
- Number of yellow marbles = 4

**Total favorable outcomes = Green + Yellow**
Total favorable outcomes = 3 + 4 = 7

### Step 3: Calculate the probability of selecting a yellow or green marble.
The probability \( P \) of an event is given by the formula:
\[ P(\text{event}) = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} \]

In this case, the event is selecting a yellow or green marble.

\[ P(\text{yellow or green}) = \frac{\text{Total favorable outcomes}}{\text{Total number of marbles}} \]
\[ P(\text{yellow or green}) = \frac{7}{10} \]

### Final Answer:
The probability that a marble chosen at random from the jar is yellow or green is \( \frac{7}{10} \).

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