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Finding the Fourth Proportional to 1,187.89, 1,780.86 and 771.85

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Solution

The fourth proportional to 1,187.89, 1,780.86 and 771.85 is: 1,157.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.89 : 1,780.86 = 771.85 : x
  2. Step 2: Convert to fraction form
    1,187.89/1,780.86 = 771.85/x
  3. Step 3: Cross multiply
    1,187.89x = 1,780.86 × 771.85
  4. Step 4: Simplify right side
    1,187.89x = 1,374,556.79
  5. Step 5: Solve for x
    x = 1,374,556.79/1,187.89
  6. Step 6: Final answer
    x = 1,157.14

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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.