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Finding the Fourth Proportional to 1,139, 1,708.75 and 645.64

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Solution

The fourth proportional to 1,139, 1,708.75 and 645.64 is: 968.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139 : 1,708.75 = 645.64 : x
  2. Step 2: Convert to fraction form
    1,139/1,708.75 = 645.64/x
  3. Step 3: Cross multiply
    1,139x = 1,708.75 × 645.64
  4. Step 4: Simplify right side
    1,139x = 1,103,234.12
  5. Step 5: Solve for x
    x = 1,103,234.12/1,139
  6. Step 6: Final answer
    x = 968.60

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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.