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Finding the Fourth Proportional to 486.40, 731.40 and 407.20

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Solution

The fourth proportional to 486.40, 731.40 and 407.20 is: 612.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    486.40 : 731.40 = 407.20 : x
  2. Step 2: Convert to fraction form
    486.40/731.40 = 407.20/x
  3. Step 3: Cross multiply
    486.40x = 731.40 × 407.20
  4. Step 4: Simplify right side
    486.40x = 297,826.08
  5. Step 5: Solve for x
    x = 297,826.08/486.40
  6. Step 6: Final answer
    x = 612.31

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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.