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Finding the Fourth Proportional to 921.12, 1,269.72 and 724.29

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Solution

The fourth proportional to 921.12, 1,269.72 and 724.29 is: 998.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.12 : 1,269.72 = 724.29 : x
  2. Step 2: Convert to fraction form
    921.12/1,269.72 = 724.29/x
  3. Step 3: Cross multiply
    921.12x = 1,269.72 × 724.29
  4. Step 4: Simplify right side
    921.12x = 919,645.50
  5. Step 5: Solve for x
    x = 919,645.50/921.12
  6. Step 6: Final answer
    x = 998.40

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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.