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Finding the Fourth Proportional to 928.32, 1,391.52 and 639.84

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Solution

The fourth proportional to 928.32, 1,391.52 and 639.84 is: 959.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    928.32 : 1,391.52 = 639.84 : x
  2. Step 2: Convert to fraction form
    928.32/1,391.52 = 639.84/x
  3. Step 3: Cross multiply
    928.32x = 1,391.52 × 639.84
  4. Step 4: Simplify right side
    928.32x = 890,350.16
  5. Step 5: Solve for x
    x = 890,350.16/928.32
  6. Step 6: Final answer
    x = 959.10

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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.