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Finding the Fourth Proportional to 978.36, 1,349.25 and 647.12

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Solution

The fourth proportional to 978.36, 1,349.25 and 647.12 is: 892.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.36 : 1,349.25 = 647.12 : x
  2. Step 2: Convert to fraction form
    978.36/1,349.25 = 647.12/x
  3. Step 3: Cross multiply
    978.36x = 1,349.25 × 647.12
  4. Step 4: Simplify right side
    978.36x = 873,119.91
  5. Step 5: Solve for x
    x = 873,119.91/978.36
  6. Step 6: Final answer
    x = 892.43

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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.