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Finding the Fourth Proportional to 1,388.31, 1,915.97 and 864.42

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Solution

The fourth proportional to 1,388.31, 1,915.97 and 864.42 is: 1,192.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.31 : 1,915.97 = 864.42 : x
  2. Step 2: Convert to fraction form
    1,388.31/1,915.97 = 864.42/x
  3. Step 3: Cross multiply
    1,388.31x = 1,915.97 × 864.42
  4. Step 4: Simplify right side
    1,388.31x = 1,656,202.79
  5. Step 5: Solve for x
    x = 1,656,202.79/1,388.31
  6. Step 6: Final answer
    x = 1,192.96

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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.