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Finding the Fourth Proportional to 687.70, 1,031.55 and 648.10

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Solution

The fourth proportional to 687.70, 1,031.55 and 648.10 is: 972.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.70 : 1,031.55 = 648.10 : x
  2. Step 2: Convert to fraction form
    687.70/1,031.55 = 648.10/x
  3. Step 3: Cross multiply
    687.70x = 1,031.55 × 648.10
  4. Step 4: Simplify right side
    687.70x = 668,547.56
  5. Step 5: Solve for x
    x = 668,547.56/687.70
  6. Step 6: Final answer
    x = 972.15

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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.