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Finding the Fourth Proportional to 919.76, 1,377.92 and 487.20

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Solution

The fourth proportional to 919.76, 1,377.92 and 487.20 is: 729.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.76 : 1,377.92 = 487.20 : x
  2. Step 2: Convert to fraction form
    919.76/1,377.92 = 487.20/x
  3. Step 3: Cross multiply
    919.76x = 1,377.92 × 487.20
  4. Step 4: Simplify right side
    919.76x = 671,322.62
  5. Step 5: Solve for x
    x = 671,322.62/919.76
  6. Step 6: Final answer
    x = 729.89

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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.