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Finding the Fourth Proportional to 2,815.30, 4,221.62 and 840.20

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Solution

The fourth proportional to 2,815.30, 4,221.62 and 840.20 is: 1,259.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,815.30 : 4,221.62 = 840.20 : x
  2. Step 2: Convert to fraction form
    2,815.30/4,221.62 = 840.20/x
  3. Step 3: Cross multiply
    2,815.30x = 4,221.62 × 840.20
  4. Step 4: Simplify right side
    2,815.30x = 3,547,005.12
  5. Step 5: Solve for x
    x = 3,547,005.12/2,815.30
  6. Step 6: Final answer
    x = 1,259.90

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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.