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Finding the Fourth Proportional to 921.72, 1,272.36 and 572.40

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Solution

The fourth proportional to 921.72, 1,272.36 and 572.40 is: 790.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.72 : 1,272.36 = 572.40 : x
  2. Step 2: Convert to fraction form
    921.72/1,272.36 = 572.40/x
  3. Step 3: Cross multiply
    921.72x = 1,272.36 × 572.40
  4. Step 4: Simplify right side
    921.72x = 728,298.86
  5. Step 5: Solve for x
    x = 728,298.86/921.72
  6. Step 6: Final answer
    x = 790.15

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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.