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Finding the Fourth Proportional to 1,408.78, 2,113.44 and 639.28

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Solution

The fourth proportional to 1,408.78, 2,113.44 and 639.28 is: 959.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,408.78 : 2,113.44 = 639.28 : x
  2. Step 2: Convert to fraction form
    1,408.78/2,113.44 = 639.28/x
  3. Step 3: Cross multiply
    1,408.78x = 2,113.44 × 639.28
  4. Step 4: Simplify right side
    1,408.78x = 1,351,079.92
  5. Step 5: Solve for x
    x = 1,351,079.92/1,408.78
  6. Step 6: Final answer
    x = 959.04

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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.