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Finding the Fourth Proportional to 1,078.69, 1,615.80 and 686.75

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Solution

The fourth proportional to 1,078.69, 1,615.80 and 686.75 is: 1,028.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,078.69 : 1,615.80 = 686.75 : x
  2. Step 2: Convert to fraction form
    1,078.69/1,615.80 = 686.75/x
  3. Step 3: Cross multiply
    1,078.69x = 1,615.80 × 686.75
  4. Step 4: Simplify right side
    1,078.69x = 1,109,647.22
  5. Step 5: Solve for x
    x = 1,109,647.22/1,078.69
  6. Step 6: Final answer
    x = 1,028.70

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.