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Finding the Fourth Proportional to 811.90, 1,217.40 and 378.52

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Solution

The fourth proportional to 811.90, 1,217.40 and 378.52 is: 567.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.90 : 1,217.40 = 378.52 : x
  2. Step 2: Convert to fraction form
    811.90/1,217.40 = 378.52/x
  3. Step 3: Cross multiply
    811.90x = 1,217.40 × 378.52
  4. Step 4: Simplify right side
    811.90x = 460,810.25
  5. Step 5: Solve for x
    x = 460,810.25/811.90
  6. Step 6: Final answer
    x = 567.57

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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.