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Finding the Fourth Proportional to 811.89, 1,120.40 and 438.86

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Solution

The fourth proportional to 811.89, 1,120.40 and 438.86 is: 605.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.89 : 1,120.40 = 438.86 : x
  2. Step 2: Convert to fraction form
    811.89/1,120.40 = 438.86/x
  3. Step 3: Cross multiply
    811.89x = 1,120.40 × 438.86
  4. Step 4: Simplify right side
    811.89x = 491,699.90
  5. Step 5: Solve for x
    x = 491,699.90/811.89
  6. Step 6: Final answer
    x = 605.63

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.