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Finding the Fourth Proportional to 687.84, 1,031.47 and 427.45

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Solution

The fourth proportional to 687.84, 1,031.47 and 427.45 is: 640.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.84 : 1,031.47 = 427.45 : x
  2. Step 2: Convert to fraction form
    687.84/1,031.47 = 427.45/x
  3. Step 3: Cross multiply
    687.84x = 1,031.47 × 427.45
  4. Step 4: Simplify right side
    687.84x = 440,903.04
  5. Step 5: Solve for x
    x = 440,903.04/687.84
  6. Step 6: Final answer
    x = 640.99

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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.