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Finding the Fourth Proportional to 811.71, 1,216.71 and 378.81

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Solution

The fourth proportional to 811.71, 1,216.71 and 378.81 is: 567.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.71 : 1,216.71 = 378.81 : x
  2. Step 2: Convert to fraction form
    811.71/1,216.71 = 378.81/x
  3. Step 3: Cross multiply
    811.71x = 1,216.71 × 378.81
  4. Step 4: Simplify right side
    811.71x = 460,901.92
  5. Step 5: Solve for x
    x = 460,901.92/811.71
  6. Step 6: Final answer
    x = 567.82

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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.