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Finding the Fourth Proportional to 987.52, 1,363.20 and 918.40

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Solution

The fourth proportional to 987.52, 1,363.20 and 918.40 is: 1,267.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.52 : 1,363.20 = 918.40 : x
  2. Step 2: Convert to fraction form
    987.52/1,363.20 = 918.40/x
  3. Step 3: Cross multiply
    987.52x = 1,363.20 × 918.40
  4. Step 4: Simplify right side
    987.52x = 1,251,962.88
  5. Step 5: Solve for x
    x = 1,251,962.88/987.52
  6. Step 6: Final answer
    x = 1,267.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.