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Finding the Fourth Proportional to 921.12, 1,381.56 and 408

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Solution

The fourth proportional to 921.12, 1,381.56 and 408 is: 611.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.12 : 1,381.56 = 408 : x
  2. Step 2: Convert to fraction form
    921.12/1,381.56 = 408/x
  3. Step 3: Cross multiply
    921.12x = 1,381.56 × 408
  4. Step 4: Simplify right side
    921.12x = 563,676.48
  5. Step 5: Solve for x
    x = 563,676.48/921.12
  6. Step 6: Final answer
    x = 611.95

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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.