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Finding the Fourth Proportional to 1,405.12, 1,939.20 and 807.70

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Solution

The fourth proportional to 1,405.12, 1,939.20 and 807.70 is: 1,114.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,405.12 : 1,939.20 = 807.70 : x
  2. Step 2: Convert to fraction form
    1,405.12/1,939.20 = 807.70/x
  3. Step 3: Cross multiply
    1,405.12x = 1,939.20 × 807.70
  4. Step 4: Simplify right side
    1,405.12x = 1,566,278.11
  5. Step 5: Solve for x
    x = 1,566,278.11/1,405.12
  6. Step 6: Final answer
    x = 1,114.70

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.