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Finding the Fourth Proportional to 721.90, 1,087.38 and 657.30

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Solution

The fourth proportional to 721.90, 1,087.38 and 657.30 is: 990.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.90 : 1,087.38 = 657.30 : x
  2. Step 2: Convert to fraction form
    721.90/1,087.38 = 657.30/x
  3. Step 3: Cross multiply
    721.90x = 1,087.38 × 657.30
  4. Step 4: Simplify right side
    721.90x = 714,734.87
  5. Step 5: Solve for x
    x = 714,734.87/721.90
  6. Step 6: Final answer
    x = 990.07

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.