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Finding the Fourth Proportional to 717.50, 987.72 and 643.80

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Solution

The fourth proportional to 717.50, 987.72 and 643.80 is: 886.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    717.50 : 987.72 = 643.80 : x
  2. Step 2: Convert to fraction form
    717.50/987.72 = 643.80/x
  3. Step 3: Cross multiply
    717.50x = 987.72 × 643.80
  4. Step 4: Simplify right side
    717.50x = 635,894.14
  5. Step 5: Solve for x
    x = 635,894.14/717.50
  6. Step 6: Final answer
    x = 886.26

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.