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Finding the Fourth Proportional to 687.18, 948.31 and 407.40

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Solution

The fourth proportional to 687.18, 948.31 and 407.40 is: 562.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    687.18 : 948.31 = 407.40 : x
  2. Step 2: Convert to fraction form
    687.18/948.31 = 407.40/x
  3. Step 3: Cross multiply
    687.18x = 948.31 × 407.40
  4. Step 4: Simplify right side
    687.18x = 386,336.92
  5. Step 5: Solve for x
    x = 386,336.92/687.18
  6. Step 6: Final answer
    x = 562.20

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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.