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Finding the Fourth Proportional to 811.18, 1,215.48 and 486.40

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Solution

The fourth proportional to 811.18, 1,215.48 and 486.40 is: 728.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.18 : 1,215.48 = 486.40 : x
  2. Step 2: Convert to fraction form
    811.18/1,215.48 = 486.40/x
  3. Step 3: Cross multiply
    811.18x = 1,215.48 × 486.40
  4. Step 4: Simplify right side
    811.18x = 591,209.47
  5. Step 5: Solve for x
    x = 591,209.47/811.18
  6. Step 6: Final answer
    x = 728.83

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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.