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Finding the Fourth Proportional to 878.50, 1,212.30 and 485.50

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Solution

The fourth proportional to 878.50, 1,212.30 and 485.50 is: 669.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.50 : 1,212.30 = 485.50 : x
  2. Step 2: Convert to fraction form
    878.50/1,212.30 = 485.50/x
  3. Step 3: Cross multiply
    878.50x = 1,212.30 × 485.50
  4. Step 4: Simplify right side
    878.50x = 588,571.65
  5. Step 5: Solve for x
    x = 588,571.65/878.50
  6. Step 6: Final answer
    x = 669.97

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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.