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Finding the Fourth Proportional to 1,389.64, 2,081.08 and 840.48

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Solution

The fourth proportional to 1,389.64, 2,081.08 and 840.48 is: 1,258.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.64 : 2,081.08 = 840.48 : x
  2. Step 2: Convert to fraction form
    1,389.64/2,081.08 = 840.48/x
  3. Step 3: Cross multiply
    1,389.64x = 2,081.08 × 840.48
  4. Step 4: Simplify right side
    1,389.64x = 1,749,106.12
  5. Step 5: Solve for x
    x = 1,749,106.12/1,389.64
  6. Step 6: Final answer
    x = 1,258.68

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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.