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Finding the Fourth Proportional to 978.13, 1,349.56 and 663.85

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Solution

The fourth proportional to 978.13, 1,349.56 and 663.85 is: 915.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.13 : 1,349.56 = 663.85 : x
  2. Step 2: Convert to fraction form
    978.13/1,349.56 = 663.85/x
  3. Step 3: Cross multiply
    978.13x = 1,349.56 × 663.85
  4. Step 4: Simplify right side
    978.13x = 895,905.41
  5. Step 5: Solve for x
    x = 895,905.41/978.13
  6. Step 6: Final answer
    x = 915.94

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.