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Finding the Fourth Proportional to 921.60, 1,380.96 and 690.12

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Solution

The fourth proportional to 921.60, 1,380.96 and 690.12 is: 1,034.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    921.60 : 1,380.96 = 690.12 : x
  2. Step 2: Convert to fraction form
    921.60/1,380.96 = 690.12/x
  3. Step 3: Cross multiply
    921.60x = 1,380.96 × 690.12
  4. Step 4: Simplify right side
    921.60x = 953,028.12
  5. Step 5: Solve for x
    x = 953,028.12/921.60
  6. Step 6: Final answer
    x = 1,034.10

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.