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Finding the Fourth Proportional to 691.11, 1,038.71 and 640.18

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Solution

The fourth proportional to 691.11, 1,038.71 and 640.18 is: 962.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.11 : 1,038.71 = 640.18 : x
  2. Step 2: Convert to fraction form
    691.11/1,038.71 = 640.18/x
  3. Step 3: Cross multiply
    691.11x = 1,038.71 × 640.18
  4. Step 4: Simplify right side
    691.11x = 664,961.37
  5. Step 5: Solve for x
    x = 664,961.37/691.11
  6. Step 6: Final answer
    x = 962.16

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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.