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Finding the Fourth Proportional to 840.15, 1,258.07 and 815.51

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Solution

The fourth proportional to 840.15, 1,258.07 and 815.51 is: 1,221.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.15 : 1,258.07 = 815.51 : x
  2. Step 2: Convert to fraction form
    840.15/1,258.07 = 815.51/x
  3. Step 3: Cross multiply
    840.15x = 1,258.07 × 815.51
  4. Step 4: Simplify right side
    840.15x = 1,025,967.73
  5. Step 5: Solve for x
    x = 1,025,967.73/840.15
  6. Step 6: Final answer
    x = 1,221.17

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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.