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Finding the Fourth Proportional to 978.12, 1,349.68 and 558.45

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Solution

The fourth proportional to 978.12, 1,349.68 and 558.45 is: 770.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.12 : 1,349.68 = 558.45 : x
  2. Step 2: Convert to fraction form
    978.12/1,349.68 = 558.45/x
  3. Step 3: Cross multiply
    978.12x = 1,349.68 × 558.45
  4. Step 4: Simplify right side
    978.12x = 753,724.65
  5. Step 5: Solve for x
    x = 753,724.65/978.12
  6. Step 6: Final answer
    x = 770.58

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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.