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Finding the Fourth Proportional to 1,311.90, 1,810.23 and 781.02

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Solution

The fourth proportional to 1,311.90, 1,810.23 and 781.02 is: 1,077.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.90 : 1,810.23 = 781.02 : x
  2. Step 2: Convert to fraction form
    1,311.90/1,810.23 = 781.02/x
  3. Step 3: Cross multiply
    1,311.90x = 1,810.23 × 781.02
  4. Step 4: Simplify right side
    1,311.90x = 1,413,825.83
  5. Step 5: Solve for x
    x = 1,413,825.83/1,311.90
  6. Step 6: Final answer
    x = 1,077.69

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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.