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Finding the Fourth Proportional to 1,187.88, 1,781.70 and 407.90

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Solution

The fourth proportional to 1,187.88, 1,781.70 and 407.90 is: 611.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.88 : 1,781.70 = 407.90 : x
  2. Step 2: Convert to fraction form
    1,187.88/1,781.70 = 407.90/x
  3. Step 3: Cross multiply
    1,187.88x = 1,781.70 × 407.90
  4. Step 4: Simplify right side
    1,187.88x = 726,758.35
  5. Step 5: Solve for x
    x = 726,758.35/1,187.88
  6. Step 6: Final answer
    x = 611.81

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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.