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Finding the Fourth Proportional to 711.40, 981.90 and 396.78

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Solution

The fourth proportional to 711.40, 981.90 and 396.78 is: 547.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    711.40 : 981.90 = 396.78 : x
  2. Step 2: Convert to fraction form
    711.40/981.90 = 396.78/x
  3. Step 3: Cross multiply
    711.40x = 981.90 × 396.78
  4. Step 4: Simplify right side
    711.40x = 389,598.28
  5. Step 5: Solve for x
    x = 389,598.28/711.40
  6. Step 6: Final answer
    x = 547.65

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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.