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Finding the Fourth Proportional to 1,247.28, 1,720.44 and 780.72

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Solution

The fourth proportional to 1,247.28, 1,720.44 and 780.72 is: 1,076.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.28 : 1,720.44 = 780.72 : x
  2. Step 2: Convert to fraction form
    1,247.28/1,720.44 = 780.72/x
  3. Step 3: Cross multiply
    1,247.28x = 1,720.44 × 780.72
  4. Step 4: Simplify right side
    1,247.28x = 1,343,181.92
  5. Step 5: Solve for x
    x = 1,343,181.92/1,247.28
  6. Step 6: Final answer
    x = 1,076.89

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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.