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Finding the Fourth Proportional to 12.15, 18.20 and 7.65

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Solution

The fourth proportional to 12.15, 18.20 and 7.65 is: 11.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    12.15 : 18.20 = 7.65 : x
  2. Step 2: Convert to fraction form
    12.15/18.20 = 7.65/x
  3. Step 3: Cross multiply
    12.15x = 18.20 × 7.65
  4. Step 4: Simplify right side
    12.15x = 139.10
  5. Step 5: Solve for x
    x = 139.10/12.15
  6. Step 6: Final answer
    x = 11.45

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.