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Finding the Fourth Proportional to 938.80, 1,408.20 and 665.20

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Solution

The fourth proportional to 938.80, 1,408.20 and 665.20 is: 997.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    938.80 : 1,408.20 = 665.20 : x
  2. Step 2: Convert to fraction form
    938.80/1,408.20 = 665.20/x
  3. Step 3: Cross multiply
    938.80x = 1,408.20 × 665.20
  4. Step 4: Simplify right side
    938.80x = 936,734.64
  5. Step 5: Solve for x
    x = 936,734.64/938.80
  6. Step 6: Final answer
    x = 997.80

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1.5x scale

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.