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Finding the Fourth Proportional to 918.98, 1,377.12 and 686.78

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Solution

The fourth proportional to 918.98, 1,377.12 and 686.78 is: 1,029.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.98 : 1,377.12 = 686.78 : x
  2. Step 2: Convert to fraction form
    918.98/1,377.12 = 686.78/x
  3. Step 3: Cross multiply
    918.98x = 1,377.12 × 686.78
  4. Step 4: Simplify right side
    918.98x = 945,778.47
  5. Step 5: Solve for x
    x = 945,778.47/918.98
  6. Step 6: Final answer
    x = 1,029.16

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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.