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Finding the Fourth Proportional to 921.85, 1,383.10 and 428.49

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Solution

The fourth proportional to 921.85, 1,383.10 and 428.49 is: 642.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.85 : 1,383.10 = 428.49 : x
  2. Step 2: Convert to fraction form
    921.85/1,383.10 = 428.49/x
  3. Step 3: Cross multiply
    921.85x = 1,383.10 × 428.49
  4. Step 4: Simplify right side
    921.85x = 592,643.45
  5. Step 5: Solve for x
    x = 592,643.45/921.85
  6. Step 6: Final answer
    x = 642.89

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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.