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Finding the Fourth Proportional to 878.60, 1,211.68 and 643.08

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Solution

The fourth proportional to 878.60, 1,211.68 and 643.08 is: 886.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.60 : 1,211.68 = 643.08 : x
  2. Step 2: Convert to fraction form
    878.60/1,211.68 = 643.08/x
  3. Step 3: Cross multiply
    878.60x = 1,211.68 × 643.08
  4. Step 4: Simplify right side
    878.60x = 779,207.17
  5. Step 5: Solve for x
    x = 779,207.17/878.60
  6. Step 6: Final answer
    x = 886.87

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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.