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Finding the Fourth Proportional to 1,189, 1,779.66 and 639.88

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Solution

The fourth proportional to 1,189, 1,779.66 and 639.88 is: 957.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,189 : 1,779.66 = 639.88 : x
  2. Step 2: Convert to fraction form
    1,189/1,779.66 = 639.88/x
  3. Step 3: Cross multiply
    1,189x = 1,779.66 × 639.88
  4. Step 4: Simplify right side
    1,189x = 1,138,768.84
  5. Step 5: Solve for x
    x = 1,138,768.84/1,189
  6. Step 6: Final answer
    x = 957.75

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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.