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Finding the Fourth Proportional to 1,318.80, 1,978.28 and 345

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Solution

The fourth proportional to 1,318.80, 1,978.28 and 345 is: 517.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.80 : 1,978.28 = 345 : x
  2. Step 2: Convert to fraction form
    1,318.80/1,978.28 = 345/x
  3. Step 3: Cross multiply
    1,318.80x = 1,978.28 × 345
  4. Step 4: Simplify right side
    1,318.80x = 682,506.60
  5. Step 5: Solve for x
    x = 682,506.60/1,318.80
  6. Step 6: Final answer
    x = 517.52

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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.