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Finding the Fourth Proportional to 687.39, 948.36 and 421.74

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Solution

The fourth proportional to 687.39, 948.36 and 421.74 is: 581.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.39 : 948.36 = 421.74 : x
  2. Step 2: Convert to fraction form
    687.39/948.36 = 421.74/x
  3. Step 3: Cross multiply
    687.39x = 948.36 × 421.74
  4. Step 4: Simplify right side
    687.39x = 399,961.35
  5. Step 5: Solve for x
    x = 399,961.35/687.39
  6. Step 6: Final answer
    x = 581.86

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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.