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Finding the Fourth Proportional to 685.40, 1,026.98 and 428.36

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Solution

The fourth proportional to 685.40, 1,026.98 and 428.36 is: 641.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.40 : 1,026.98 = 428.36 : x
  2. Step 2: Convert to fraction form
    685.40/1,026.98 = 428.36/x
  3. Step 3: Cross multiply
    685.40x = 1,026.98 × 428.36
  4. Step 4: Simplify right side
    685.40x = 439,917.15
  5. Step 5: Solve for x
    x = 439,917.15/685.40
  6. Step 6: Final answer
    x = 641.84

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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.