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Finding the Fourth Proportional to 1,187, 1,638.08 and 663.12

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Solution

The fourth proportional to 1,187, 1,638.08 and 663.12 is: 915.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187 : 1,638.08 = 663.12 : x
  2. Step 2: Convert to fraction form
    1,187/1,638.08 = 663.12/x
  3. Step 3: Cross multiply
    1,187x = 1,638.08 × 663.12
  4. Step 4: Simplify right side
    1,187x = 1,086,243.61
  5. Step 5: Solve for x
    x = 1,086,243.61/1,187
  6. Step 6: Final answer
    x = 915.12

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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.