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Finding the Fourth Proportional to 728.28, 1,005.42 and 492.40

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Solution

The fourth proportional to 728.28, 1,005.42 and 492.40 is: 679.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.28 : 1,005.42 = 492.40 : x
  2. Step 2: Convert to fraction form
    728.28/1,005.42 = 492.40/x
  3. Step 3: Cross multiply
    728.28x = 1,005.42 × 492.40
  4. Step 4: Simplify right side
    728.28x = 495,068.81
  5. Step 5: Solve for x
    x = 495,068.81/728.28
  6. Step 6: Final answer
    x = 679.78

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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.