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Finding the Fourth Proportional to 428.40, 642.96 and 326.34

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Solution

The fourth proportional to 428.40, 642.96 and 326.34 is: 489.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.40 : 642.96 = 326.34 : x
  2. Step 2: Convert to fraction form
    428.40/642.96 = 326.34/x
  3. Step 3: Cross multiply
    428.40x = 642.96 × 326.34
  4. Step 4: Simplify right side
    428.40x = 209,823.57
  5. Step 5: Solve for x
    x = 209,823.57/428.40
  6. Step 6: Final answer
    x = 489.78

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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.