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Finding the Fourth Proportional to 815.39, 1,221.62 and 686.19

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Solution

The fourth proportional to 815.39, 1,221.62 and 686.19 is: 1,028.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.39 : 1,221.62 = 686.19 : x
  2. Step 2: Convert to fraction form
    815.39/1,221.62 = 686.19/x
  3. Step 3: Cross multiply
    815.39x = 1,221.62 × 686.19
  4. Step 4: Simplify right side
    815.39x = 838,264.58
  5. Step 5: Solve for x
    x = 838,264.58/815.39
  6. Step 6: Final answer
    x = 1,028.06

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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.