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Finding the Fourth Proportional to 1,139.40, 1,708.55 and 408.80

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Solution

The fourth proportional to 1,139.40, 1,708.55 and 408.80 is: 612.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.40 : 1,708.55 = 408.80 : x
  2. Step 2: Convert to fraction form
    1,139.40/1,708.55 = 408.80/x
  3. Step 3: Cross multiply
    1,139.40x = 1,708.55 × 408.80
  4. Step 4: Simplify right side
    1,139.40x = 698,444.65
  5. Step 5: Solve for x
    x = 698,444.65/1,139.40
  6. Step 6: Final answer
    x = 612.99

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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.