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Finding the Fourth Proportional to 1,391.78, 2,087.68 and 417.82

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Solution

The fourth proportional to 1,391.78, 2,087.68 and 417.82 is: 626.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.78 : 2,087.68 = 417.82 : x
  2. Step 2: Convert to fraction form
    1,391.78/2,087.68 = 417.82/x
  3. Step 3: Cross multiply
    1,391.78x = 2,087.68 × 417.82
  4. Step 4: Simplify right side
    1,391.78x = 872,274.46
  5. Step 5: Solve for x
    x = 872,274.46/1,391.78
  6. Step 6: Final answer
    x = 626.74

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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.