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Finding the Fourth Proportional to 1,247.68, 1,721.28 and 782.08

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Solution

The fourth proportional to 1,247.68, 1,721.28 and 782.08 is: 1,078.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,247.68 : 1,721.28 = 782.08 : x
  2. Step 2: Convert to fraction form
    1,247.68/1,721.28 = 782.08/x
  3. Step 3: Cross multiply
    1,247.68x = 1,721.28 × 782.08
  4. Step 4: Simplify right side
    1,247.68x = 1,346,178.66
  5. Step 5: Solve for x
    x = 1,346,178.66/1,247.68
  6. Step 6: Final answer
    x = 1,078.95

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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.