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Finding the Fourth Proportional to 780.31, 1,170.51 and 665.56

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Solution

The fourth proportional to 780.31, 1,170.51 and 665.56 is: 998.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.31 : 1,170.51 = 665.56 : x
  2. Step 2: Convert to fraction form
    780.31/1,170.51 = 665.56/x
  3. Step 3: Cross multiply
    780.31x = 1,170.51 × 665.56
  4. Step 4: Simplify right side
    780.31x = 779,044.64
  5. Step 5: Solve for x
    x = 779,044.64/780.31
  6. Step 6: Final answer
    x = 998.38

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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.