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Finding the Fourth Proportional to 898.40, 1,347.60 and 639.20

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Solution

The fourth proportional to 898.40, 1,347.60 and 639.20 is: 958.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    898.40 : 1,347.60 = 639.20 : x
  2. Step 2: Convert to fraction form
    898.40/1,347.60 = 639.20/x
  3. Step 3: Cross multiply
    898.40x = 1,347.60 × 639.20
  4. Step 4: Simplify right side
    898.40x = 861,385.92
  5. Step 5: Solve for x
    x = 861,385.92/898.40
  6. Step 6: Final answer
    x = 958.80

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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.