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Finding the Fourth Proportional to 821.62, 1,231.40 and 561.20

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Solution

The fourth proportional to 821.62, 1,231.40 and 561.20 is: 841.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.62 : 1,231.40 = 561.20 : x
  2. Step 2: Convert to fraction form
    821.62/1,231.40 = 561.20/x
  3. Step 3: Cross multiply
    821.62x = 1,231.40 × 561.20
  4. Step 4: Simplify right side
    821.62x = 691,061.68
  5. Step 5: Solve for x
    x = 691,061.68/821.62
  6. Step 6: Final answer
    x = 841.10

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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.