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Finding the Fourth Proportional to 809.10, 1,213.40 and 261.18

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Solution

The fourth proportional to 809.10, 1,213.40 and 261.18 is: 391.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.10 : 1,213.40 = 261.18 : x
  2. Step 2: Convert to fraction form
    809.10/1,213.40 = 261.18/x
  3. Step 3: Cross multiply
    809.10x = 1,213.40 × 261.18
  4. Step 4: Simplify right side
    809.10x = 316,914.51
  5. Step 5: Solve for x
    x = 316,914.51/809.10
  6. Step 6: Final answer
    x = 391.69

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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.