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Finding the Fourth Proportional to 1,247.78, 1,721.13 and 782.03

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Solution

The fourth proportional to 1,247.78, 1,721.13 and 782.03 is: 1,078.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.78 : 1,721.13 = 782.03 : x
  2. Step 2: Convert to fraction form
    1,247.78/1,721.13 = 782.03/x
  3. Step 3: Cross multiply
    1,247.78x = 1,721.13 × 782.03
  4. Step 4: Simplify right side
    1,247.78x = 1,345,975.29
  5. Step 5: Solve for x
    x = 1,345,975.29/1,247.78
  6. Step 6: Final answer
    x = 1,078.70

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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.