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Finding the Fourth Proportional to 840.57, 1,258.91 and 811.38

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Solution

The fourth proportional to 840.57, 1,258.91 and 811.38 is: 1,215.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.57 : 1,258.91 = 811.38 : x
  2. Step 2: Convert to fraction form
    840.57/1,258.91 = 811.38/x
  3. Step 3: Cross multiply
    840.57x = 1,258.91 × 811.38
  4. Step 4: Simplify right side
    840.57x = 1,021,458.10
  5. Step 5: Solve for x
    x = 1,021,458.10/840.57
  6. Step 6: Final answer
    x = 1,215.20

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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.