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Finding the Fourth Proportional to 840.45, 1,258.72 and 811.26

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Solution

The fourth proportional to 840.45, 1,258.72 and 811.26 is: 1,215.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.45 : 1,258.72 = 811.26 : x
  2. Step 2: Convert to fraction form
    840.45/1,258.72 = 811.26/x
  3. Step 3: Cross multiply
    840.45x = 1,258.72 × 811.26
  4. Step 4: Simplify right side
    840.45x = 1,021,149.19
  5. Step 5: Solve for x
    x = 1,021,149.19/840.45
  6. Step 6: Final answer
    x = 1,215.00

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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.