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Finding the Fourth Proportional to 840.80, 1,160.40 and 813.92

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Solution

The fourth proportional to 840.80, 1,160.40 and 813.92 is: 1,123.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.80 : 1,160.40 = 813.92 : x
  2. Step 2: Convert to fraction form
    840.80/1,160.40 = 813.92/x
  3. Step 3: Cross multiply
    840.80x = 1,160.40 × 813.92
  4. Step 4: Simplify right side
    840.80x = 944,472.77
  5. Step 5: Solve for x
    x = 944,472.77/840.80
  6. Step 6: Final answer
    x = 1,123.30

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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.