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Finding the Fourth Proportional to 780.90, 1,171.45 and 287.34

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Solution

The fourth proportional to 780.90, 1,171.45 and 287.34 is: 431.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.90 : 1,171.45 = 287.34 : x
  2. Step 2: Convert to fraction form
    780.90/1,171.45 = 287.34/x
  3. Step 3: Cross multiply
    780.90x = 1,171.45 × 287.34
  4. Step 4: Simplify right side
    780.90x = 336,604.44
  5. Step 5: Solve for x
    x = 336,604.44/780.90
  6. Step 6: Final answer
    x = 431.05

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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.