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Finding the Fourth Proportional to 638.40, 880.08 and 428.20

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Solution

The fourth proportional to 638.40, 880.08 and 428.20 is: 590.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.40 : 880.08 = 428.20 : x
  2. Step 2: Convert to fraction form
    638.40/880.08 = 428.20/x
  3. Step 3: Cross multiply
    638.40x = 880.08 × 428.20
  4. Step 4: Simplify right side
    638.40x = 376,850.26
  5. Step 5: Solve for x
    x = 376,850.26/638.40
  6. Step 6: Final answer
    x = 590.30

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1.5x scale

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.