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Finding the Fourth Proportional to 1,186.56, 1,779.83 and 639

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Solution

The fourth proportional to 1,186.56, 1,779.83 and 639 is: 958.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,186.56 : 1,779.83 = 639 : x
  2. Step 2: Convert to fraction form
    1,186.56/1,779.83 = 639/x
  3. Step 3: Cross multiply
    1,186.56x = 1,779.83 × 639
  4. Step 4: Simplify right side
    1,186.56x = 1,137,308.18
  5. Step 5: Solve for x
    x = 1,137,308.18/1,186.56
  6. Step 6: Final answer
    x = 958.49

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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.