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Finding the Fourth Proportional to 1,121.39, 1,682.24 and 390.77

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Solution

The fourth proportional to 1,121.39, 1,682.24 and 390.77 is: 586.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.39 : 1,682.24 = 390.77 : x
  2. Step 2: Convert to fraction form
    1,121.39/1,682.24 = 390.77/x
  3. Step 3: Cross multiply
    1,121.39x = 1,682.24 × 390.77
  4. Step 4: Simplify right side
    1,121.39x = 657,377.63
  5. Step 5: Solve for x
    x = 657,377.63/1,121.39
  6. Step 6: Final answer
    x = 586.21

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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.