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Finding the Fourth Proportional to 931.88, 1,398.78 and 687.60

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Solution

The fourth proportional to 931.88, 1,398.78 and 687.60 is: 1,032.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.88 : 1,398.78 = 687.60 : x
  2. Step 2: Convert to fraction form
    931.88/1,398.78 = 687.60/x
  3. Step 3: Cross multiply
    931.88x = 1,398.78 × 687.60
  4. Step 4: Simplify right side
    931.88x = 961,801.13
  5. Step 5: Solve for x
    x = 961,801.13/931.88
  6. Step 6: Final answer
    x = 1,032.11

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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.