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Finding the Fourth Proportional to 1,391.85, 2,087.61 and 611.45

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Solution

The fourth proportional to 1,391.85, 2,087.61 and 611.45 is: 917.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.85 : 2,087.61 = 611.45 : x
  2. Step 2: Convert to fraction form
    1,391.85/2,087.61 = 611.45/x
  3. Step 3: Cross multiply
    1,391.85x = 2,087.61 × 611.45
  4. Step 4: Simplify right side
    1,391.85x = 1,276,464.23
  5. Step 5: Solve for x
    x = 1,276,464.23/1,391.85
  6. Step 6: Final answer
    x = 917.10

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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.