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Finding the Fourth Proportional to 869.68, 1,200.72 and 636.40

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Solution

The fourth proportional to 869.68, 1,200.72 and 636.40 is: 878.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.68 : 1,200.72 = 636.40 : x
  2. Step 2: Convert to fraction form
    869.68/1,200.72 = 636.40/x
  3. Step 3: Cross multiply
    869.68x = 1,200.72 × 636.40
  4. Step 4: Simplify right side
    869.68x = 764,138.21
  5. Step 5: Solve for x
    x = 764,138.21/869.68
  6. Step 6: Final answer
    x = 878.64

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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.