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Finding the Fourth Proportional to 878.28, 1,211.90 and 505.12

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Solution

The fourth proportional to 878.28, 1,211.90 and 505.12 is: 696.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.28 : 1,211.90 = 505.12 : x
  2. Step 2: Convert to fraction form
    878.28/1,211.90 = 505.12/x
  3. Step 3: Cross multiply
    878.28x = 1,211.90 × 505.12
  4. Step 4: Simplify right side
    878.28x = 612,152.59
  5. Step 5: Solve for x
    x = 612,152.59/878.28
  6. Step 6: Final answer
    x = 696.99

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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.