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A bag contains 20 colored marbles. Complete the table below to show the probability of picking each color at random and the number of each color marble in the bag.

What is the probability, as a percentage, of picking a yellow marble at random? How many yellow marbles are in the bag?

| Colour | Probability | Number of marbles |
|--------|-------------|-------------------|
| Red | 10% | |
| Orange | | 8 |
| Blue | 15% | |
| Yellow | | |

Sagot :

Sure, let's provide a detailed step-by-step solution:

1. Red Marbles:
- Given that the probability of picking a red marble is [tex]$10\%$[/tex].
- Since there are a total of 20 marbles:
- The number of red marbles [tex]\[ = 10\% \times 20 = 0.10 \times 20 = 2 \][/tex]

2. Orange Marbles:
- We are given that there are 8 orange marbles in the bag.
- The probability of picking an orange marble can be calculated as:
- [tex]\[ \frac{\text{Number of orange marbles}}{\text{Total number of marbles}} = \frac{8}{20} = 0.4 \text{ (or 40\%)} \][/tex]

3. Blue Marbles:
- Given that the probability of picking a blue marble is [tex]$15\%$[/tex].
- The number of blue marbles [tex]\[ = 15\% \times 20 = 0.15 \times 20 = 3 \][/tex]

4. Yellow Marbles:
- First, we need to determine the total number of red, orange, and blue marbles:
- [tex]\[ \text{Red marbles} + \text{Orange marbles} + \text{Blue marbles} = 2 + 8 + 3 = 13 \][/tex]
- Therefore, the number of yellow marbles:
- [tex]\[ \text{Total marbles} - (\text{Red marbles} + \text{Orange marbles} + \text{Blue marbles}) = 20 - 13 = 7 \][/tex]
- The probability of picking a yellow marble:
- [tex]\[ \frac{\text{Number of yellow marbles}}{\text{Total number of marbles}} = \frac{7}{20} \][/tex]
- Converting this to a percentage:
- [tex]\[ \frac{7}{20} \times 100\% = 35\% \][/tex]

So, the completed table and the answers to the questions are:

\begin{tabular}{|c|c|c|}
\hline Colour & Probability & Number of marbles \\
\hline Red & [tex]$10\%$[/tex] & 2 \\
\hline Orange & [tex]$40\%$[/tex] & 8 \\
\hline Blue & [tex]$15\%$[/tex] & 3 \\
\hline Yellow & [tex]$35\%$[/tex] & 7 \\
\hline
\end{tabular}

- The probability of picking a yellow marble at random is [tex]$35\%$[/tex].
- There are 7 yellow marbles in the bag.