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Finding the Fourth Proportional to 1,287.32, 1,775.93 and 789.78

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Solution

The fourth proportional to 1,287.32, 1,775.93 and 789.78 is: 1,089.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.32 : 1,775.93 = 789.78 : x
  2. Step 2: Convert to fraction form
    1,287.32/1,775.93 = 789.78/x
  3. Step 3: Cross multiply
    1,287.32x = 1,775.93 × 789.78
  4. Step 4: Simplify right side
    1,287.32x = 1,402,590.05
  5. Step 5: Solve for x
    x = 1,402,590.05/1,287.32
  6. Step 6: Final answer
    x = 1,089.54

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.