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Finding the Fourth Proportional to 787.89, 1,087.52 and 631.61

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Solution

The fourth proportional to 787.89, 1,087.52 and 631.61 is: 871.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.89 : 1,087.52 = 631.61 : x
  2. Step 2: Convert to fraction form
    787.89/1,087.52 = 631.61/x
  3. Step 3: Cross multiply
    787.89x = 1,087.52 × 631.61
  4. Step 4: Simplify right side
    787.89x = 686,888.51
  5. Step 5: Solve for x
    x = 686,888.51/787.89
  6. Step 6: Final answer
    x = 871.81

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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.