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Finding the Fourth Proportional to 691.41, 1,031.78 and 617.50

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Solution

The fourth proportional to 691.41, 1,031.78 and 617.50 is: 921.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.41 : 1,031.78 = 617.50 : x
  2. Step 2: Convert to fraction form
    691.41/1,031.78 = 617.50/x
  3. Step 3: Cross multiply
    691.41x = 1,031.78 × 617.50
  4. Step 4: Simplify right side
    691.41x = 637,124.15
  5. Step 5: Solve for x
    x = 637,124.15/691.41
  6. Step 6: Final answer
    x = 921.49

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.