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Finding the Fourth Proportional to 1,121.61, 1,681.61 and 505.61

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Solution

The fourth proportional to 1,121.61, 1,681.61 and 505.61 is: 758.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.61 : 1,681.61 = 505.61 : x
  2. Step 2: Convert to fraction form
    1,121.61/1,681.61 = 505.61/x
  3. Step 3: Cross multiply
    1,121.61x = 1,681.61 × 505.61
  4. Step 4: Simplify right side
    1,121.61x = 850,227.90
  5. Step 5: Solve for x
    x = 850,227.90/1,121.61
  6. Step 6: Final answer
    x = 758.04

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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.