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Finding the Fourth Proportional to 978.96, 1,467.80 and 431.20

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Solution

The fourth proportional to 978.96, 1,467.80 and 431.20 is: 646.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.96 : 1,467.80 = 431.20 : x
  2. Step 2: Convert to fraction form
    978.96/1,467.80 = 431.20/x
  3. Step 3: Cross multiply
    978.96x = 1,467.80 × 431.20
  4. Step 4: Simplify right side
    978.96x = 632,915.36
  5. Step 5: Solve for x
    x = 632,915.36/978.96
  6. Step 6: Final answer
    x = 646.52

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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.