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Finding the Fourth Proportional to 609.40, 840 and 478.20

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Solution

The fourth proportional to 609.40, 840 and 478.20 is: 659.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    609.40 : 840 = 478.20 : x
  2. Step 2: Convert to fraction form
    609.40/840 = 478.20/x
  3. Step 3: Cross multiply
    609.40x = 840 × 478.20
  4. Step 4: Simplify right side
    609.40x = 401,688
  5. Step 5: Solve for x
    x = 401,688/609.40
  6. Step 6: Final answer
    x = 659.15

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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.