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Finding the Fourth Proportional to 978.40, 1,467.72 and 430.72

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Solution

The fourth proportional to 978.40, 1,467.72 and 430.72 is: 646.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.40 : 1,467.72 = 430.72 : x
  2. Step 2: Convert to fraction form
    978.40/1,467.72 = 430.72/x
  3. Step 3: Cross multiply
    978.40x = 1,467.72 × 430.72
  4. Step 4: Simplify right side
    978.40x = 632,176.36
  5. Step 5: Solve for x
    x = 632,176.36/978.40
  6. Step 6: Final answer
    x = 646.13

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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.