The fourth proportional to 0.12, 0.21, 8 is :

Options

A. 8.9
B. 56
C. 14
D. 17

Answer

To find the fourth proportional to the numbers 0.12, 0.21, and 8, we can use the concept of proportionality. The fourth proportional \( x \) can be found using the formula:

\[ \frac{A}{B} = \frac{C}{x} \]

Where:
- \( A = 0.12 \)
- \( B = 0.21 \)
- \( C = 8 \)

### Step 1: Set up the proportion
We can set up the proportion as follows:

\[ \frac{0.12}{0.21} = \frac{8}{x} \]

### Step 2: Cross-multiply
Cross-multiplying gives us:

\[ 0.12 \cdot x = 0.21 \cdot 8 \]

### Step 3: Calculate \( 0.21 \cdot 8 \)
Now, we calculate \( 0.21 \cdot 8 \):

\[ 0.21 \cdot 8 = 1.68 \]

### Step 4: Substitute back into the equation
Now we substitute this back into our equation:

\[ 0.12 \cdot x = 1.68 \]

### Step 5: Solve for \( x \)
To find \( x \), we divide both sides by 0.12:

\[ x = \frac{1.68}{0.12} \]

### Step 6: Perform the division
Now we perform the division:

\[ x = 14 \]

Thus, the fourth proportional to 0.12, 0.21, and 8 is **14**.

### Final Answer:
The fourth proportional is **14**.

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