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Finding the Fourth Proportional to 921.28, 1,272 and 660.64

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Solution

The fourth proportional to 921.28, 1,272 and 660.64 is: 912.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.28 : 1,272 = 660.64 : x
  2. Step 2: Convert to fraction form
    921.28/1,272 = 660.64/x
  3. Step 3: Cross multiply
    921.28x = 1,272 × 660.64
  4. Step 4: Simplify right side
    921.28x = 840,334.08
  5. Step 5: Solve for x
    x = 840,334.08/921.28
  6. Step 6: Final answer
    x = 912.14

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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.