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Finding the Fourth Proportional to 1,311.17, 1,809 and 807.21

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Solution

The fourth proportional to 1,311.17, 1,809 and 807.21 is: 1,113.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.17 : 1,809 = 807.21 : x
  2. Step 2: Convert to fraction form
    1,311.17/1,809 = 807.21/x
  3. Step 3: Cross multiply
    1,311.17x = 1,809 × 807.21
  4. Step 4: Simplify right side
    1,311.17x = 1,460,242.89
  5. Step 5: Solve for x
    x = 1,460,242.89/1,311.17
  6. Step 6: Final answer
    x = 1,113.70

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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.