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Finding the Fourth Proportional to 878.40, 1,211.70 and 558.78

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Solution

The fourth proportional to 878.40, 1,211.70 and 558.78 is: 770.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.40 : 1,211.70 = 558.78 : x
  2. Step 2: Convert to fraction form
    878.40/1,211.70 = 558.78/x
  3. Step 3: Cross multiply
    878.40x = 1,211.70 × 558.78
  4. Step 4: Simplify right side
    878.40x = 677,073.73
  5. Step 5: Solve for x
    x = 677,073.73/878.40
  6. Step 6: Final answer
    x = 770.80

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Double scale
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1.5x scale

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.