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Finding the Fourth Proportional to 931.92, 1,398.69 and 643.56

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Solution

The fourth proportional to 931.92, 1,398.69 and 643.56 is: 965.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.92 : 1,398.69 = 643.56 : x
  2. Step 2: Convert to fraction form
    931.92/1,398.69 = 643.56/x
  3. Step 3: Cross multiply
    931.92x = 1,398.69 × 643.56
  4. Step 4: Simplify right side
    931.92x = 900,140.94
  5. Step 5: Solve for x
    x = 900,140.94/931.92
  6. Step 6: Final answer
    x = 965.90

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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.