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Finding the Fourth Proportional to 815.21, 1,221.33 and 686.01

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Solution

The fourth proportional to 815.21, 1,221.33 and 686.01 is: 1,027.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.21 : 1,221.33 = 686.01 : x
  2. Step 2: Convert to fraction form
    815.21/1,221.33 = 686.01/x
  3. Step 3: Cross multiply
    815.21x = 1,221.33 × 686.01
  4. Step 4: Simplify right side
    815.21x = 837,844.59
  5. Step 5: Solve for x
    x = 837,844.59/815.21
  6. Step 6: Final answer
    x = 1,027.77

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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.