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Finding the Fourth Proportional to 821.70, 1,231.20 and 705.60

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Solution

The fourth proportional to 821.70, 1,231.20 and 705.60 is: 1,057.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.70 : 1,231.20 = 705.60 : x
  2. Step 2: Convert to fraction form
    821.70/1,231.20 = 705.60/x
  3. Step 3: Cross multiply
    821.70x = 1,231.20 × 705.60
  4. Step 4: Simplify right side
    821.70x = 868,734.72
  5. Step 5: Solve for x
    x = 868,734.72/821.70
  6. Step 6: Final answer
    x = 1,057.24

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.