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Finding the Fourth Proportional to 721.08, 1,081.74 and 643.53

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Solution

The fourth proportional to 721.08, 1,081.74 and 643.53 is: 965.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    721.08 : 1,081.74 = 643.53 : x
  2. Step 2: Convert to fraction form
    721.08/1,081.74 = 643.53/x
  3. Step 3: Cross multiply
    721.08x = 1,081.74 × 643.53
  4. Step 4: Simplify right side
    721.08x = 696,132.14
  5. Step 5: Solve for x
    x = 696,132.14/721.08
  6. Step 6: Final answer
    x = 965.40

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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.