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Finding the Fourth Proportional to 921.28, 1,269.88 and 721.77

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Solution

The fourth proportional to 921.28, 1,269.88 and 721.77 is: 994.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.28 : 1,269.88 = 721.77 : x
  2. Step 2: Convert to fraction form
    921.28/1,269.88 = 721.77/x
  3. Step 3: Cross multiply
    921.28x = 1,269.88 × 721.77
  4. Step 4: Simplify right side
    921.28x = 916,561.29
  5. Step 5: Solve for x
    x = 916,561.29/921.28
  6. Step 6: Final answer
    x = 994.88

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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.