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Finding the Fourth Proportional to 1,247.31, 1,720.87 and 805.51

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Solution

The fourth proportional to 1,247.31, 1,720.87 and 805.51 is: 1,111.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.31 : 1,720.87 = 805.51 : x
  2. Step 2: Convert to fraction form
    1,247.31/1,720.87 = 805.51/x
  3. Step 3: Cross multiply
    1,247.31x = 1,720.87 × 805.51
  4. Step 4: Simplify right side
    1,247.31x = 1,386,177.99
  5. Step 5: Solve for x
    x = 1,386,177.99/1,247.31
  6. Step 6: Final answer
    x = 1,111.33

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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.