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Finding the Fourth Proportional to 1,187.21, 1,638.41 and 663.21

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Solution

The fourth proportional to 1,187.21, 1,638.41 and 663.21 is: 915.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.21 : 1,638.41 = 663.21 : x
  2. Step 2: Convert to fraction form
    1,187.21/1,638.41 = 663.21/x
  3. Step 3: Cross multiply
    1,187.21x = 1,638.41 × 663.21
  4. Step 4: Simplify right side
    1,187.21x = 1,086,598.39
  5. Step 5: Solve for x
    x = 1,086,598.39/1,187.21
  6. Step 6: Final answer
    x = 915.26

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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.