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Finding the Fourth Proportional to 1,320.40, 1,821.70 and 878.56

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Solution

The fourth proportional to 1,320.40, 1,821.70 and 878.56 is: 1,212.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.40 : 1,821.70 = 878.56 : x
  2. Step 2: Convert to fraction form
    1,320.40/1,821.70 = 878.56/x
  3. Step 3: Cross multiply
    1,320.40x = 1,821.70 × 878.56
  4. Step 4: Simplify right side
    1,320.40x = 1,600,473.09
  5. Step 5: Solve for x
    x = 1,600,473.09/1,320.40
  6. Step 6: Final answer
    x = 1,212.11

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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.