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Finding the Fourth Proportional to 988.20, 1,363.77 and 840.78

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Solution

The fourth proportional to 988.20, 1,363.77 and 840.78 is: 1,160.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    988.20 : 1,363.77 = 840.78 : x
  2. Step 2: Convert to fraction form
    988.20/1,363.77 = 840.78/x
  3. Step 3: Cross multiply
    988.20x = 1,363.77 × 840.78
  4. Step 4: Simplify right side
    988.20x = 1,146,630.54
  5. Step 5: Solve for x
    x = 1,146,630.54/988.20
  6. Step 6: Final answer
    x = 1,160.32

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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.