High School

There are only blue counters, green counters, red counters, and yellow counters in a bag. The table shows the number of blue counters in the bag:

[tex]
\[
\begin{tabular}{|c|c|c|c|c|}
\hline
Colour & Blue & Green & Red & Yellow \\
\hline
Number of counters & 30 & & & \\
\hline
\end{tabular}
\]
[/tex]

There is a total of 100 counters in the bag. Ashin takes a counter at random from the bag.

(a) Find the probability that the counter is not blue.

The ratio of the number of blue counters to the number of green counters is [tex]2:3[/tex].

(b) Work out the number of green counters in the bag.

Answer :

  • The probability of the counter not being blue is 0.7.
  • The number of green counters is 45.

Given Information:

  • The bag contains blue, green, red, and yellow counters.
  • Total counters = 100
  • Number of blue counters = 30
  • The ratio of blue to green counters is 2:3

Part (a): Probability that the counter is not blue

Find the number of counters that are not blue:

Total counters - Blue counters

= 100 - 30

= 70

Probability formula:

Probability = (Number of not blue counters) / (Total counters)

= 70 / 100

= 0.7

The probability of not picking a blue counter is 0.7.

Part (b): Finding the number of green counters

Let the number of green counters be G.

The ratio of blue to green is 2:3, so we set up a proportion:

30 / G = 2 / 3

30 × 3 = 2 × G

90 = 2G

Solve for G:

G = 90 / 2

G = 45

The number of green counters is 45.

Sure! Let's go through the solution step by step.

### (a) Finding the probability that the counter is not blue:

1. Total number of counters in the bag:
We know from the problem that there are a total of 100 counters in the bag.

2. Number of blue counters:
The table tells us there are 30 blue counters.

3. Number of counters that are not blue:
To find how many counters are not blue, subtract the number of blue counters from the total number of counters:
[tex]\[ \text{Not blue counters} = \text{Total counters} - \text{Blue counters} = 100 - 30 = 70 \][/tex]

4. Probability that the counter is not blue:
Probability is calculated by dividing the number of favorable outcomes by the total number of possible outcomes. So the probability that a counter taken at random is not blue is:
[tex]\[ \text{Probability not blue} = \frac{\text{Not blue counters}}{\text{Total counters}} = \frac{70}{100} = 0.7 \][/tex]

### (b) Working out the number of green counters:

1. Ratio of blue counters to green counters:
We are told the ratio of blue counters to green counters is 2:3.

2. Using the ratio to find the number of green counters:
The given ratio can be written as:
[tex]\[ \frac{\text{Blue counters}}{\text{Green counters}} = \frac{2}{3} \][/tex]

3. Calculate the number of green counters:
Rearrange the ratio equation to solve for green counters:
[tex]\[ \text{Green counters} = \frac{3}{2} \times \text{Blue counters} \][/tex]
Substitute the number of blue counters:
[tex]\[ \text{Green counters} = \frac{3}{2} \times 30 = 45 \][/tex]

Therefore, the probability that a randomly selected counter is not blue is 0.7, and there are 45 green counters in the bag.