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Finding the Fourth Proportional to 869.78, 1,199.94 and 636.50

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Solution

The fourth proportional to 869.78, 1,199.94 and 636.50 is: 878.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.78 : 1,199.94 = 636.50 : x
  2. Step 2: Convert to fraction form
    869.78/1,199.94 = 636.50/x
  3. Step 3: Cross multiply
    869.78x = 1,199.94 × 636.50
  4. Step 4: Simplify right side
    869.78x = 763,761.81
  5. Step 5: Solve for x
    x = 763,761.81/869.78
  6. Step 6: Final answer
    x = 878.11

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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.