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Finding the Fourth Proportional to 1,318.60, 1,978.26 and 947.71

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Solution

The fourth proportional to 1,318.60, 1,978.26 and 947.71 is: 1,421.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.60 : 1,978.26 = 947.71 : x
  2. Step 2: Convert to fraction form
    1,318.60/1,978.26 = 947.71/x
  3. Step 3: Cross multiply
    1,318.60x = 1,978.26 × 947.71
  4. Step 4: Simplify right side
    1,318.60x = 1,874,816.78
  5. Step 5: Solve for x
    x = 1,874,816.78/1,318.60
  6. Step 6: Final answer
    x = 1,421.82

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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.