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Finding the Fourth Proportional to 781.41, 1,077.90 and 515.90

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Solution

The fourth proportional to 781.41, 1,077.90 and 515.90 is: 711.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.41 : 1,077.90 = 515.90 : x
  2. Step 2: Convert to fraction form
    781.41/1,077.90 = 515.90/x
  3. Step 3: Cross multiply
    781.41x = 1,077.90 × 515.90
  4. Step 4: Simplify right side
    781.41x = 556,088.61
  5. Step 5: Solve for x
    x = 556,088.61/781.41
  6. Step 6: Final answer
    x = 711.65

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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.