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Finding the Fourth Proportional to 620.92, 857.90 and 491

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Solution

The fourth proportional to 620.92, 857.90 and 491 is: 678.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.92 : 857.90 = 491 : x
  2. Step 2: Convert to fraction form
    620.92/857.90 = 491/x
  3. Step 3: Cross multiply
    620.92x = 857.90 × 491
  4. Step 4: Simplify right side
    620.92x = 421,228.90
  5. Step 5: Solve for x
    x = 421,228.90/620.92
  6. Step 6: Final answer
    x = 678.39

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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.