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Finding the Fourth Proportional to 783.36, 1,078.56 and 689.76

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Solution

The fourth proportional to 783.36, 1,078.56 and 689.76 is: 949.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    783.36 : 1,078.56 = 689.76 : x
  2. Step 2: Convert to fraction form
    783.36/1,078.56 = 689.76/x
  3. Step 3: Cross multiply
    783.36x = 1,078.56 × 689.76
  4. Step 4: Simplify right side
    783.36x = 743,947.55
  5. Step 5: Solve for x
    x = 743,947.55/783.36
  6. Step 6: Final answer
    x = 949.69

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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.