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Finding the Fourth Proportional to 1,139.85, 1,709.86 and 318.12

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Solution

The fourth proportional to 1,139.85, 1,709.86 and 318.12 is: 477.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.85 : 1,709.86 = 318.12 : x
  2. Step 2: Convert to fraction form
    1,139.85/1,709.86 = 318.12/x
  3. Step 3: Cross multiply
    1,139.85x = 1,709.86 × 318.12
  4. Step 4: Simplify right side
    1,139.85x = 543,940.66
  5. Step 5: Solve for x
    x = 543,940.66/1,139.85
  6. Step 6: Final answer
    x = 477.20

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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.